Programs & Examples On #Htonl

Understanding INADDR_ANY for socket programming

  1. bind() of INADDR_ANY does NOT "generate a random IP". It binds the socket to all available interfaces.

  2. For a server, you typically want to bind to all interfaces - not just "localhost".

  3. If you wish to bind your socket to localhost only, the syntax would be my_sockaddress.sin_addr.s_addr = inet_addr("");, then call bind(my_socket, (SOCKADDR *) &my_sockaddr, ...).

  4. As it happens, INADDR_ANY is a constant that happens to equal "zero":

    # define INADDR_ANY ((unsigned long int) 0x00000000)
    # define INADDR_NONE    0xffffffff
    # define INPORT_ANY 0
  5. If you're not already familiar with it, I urge you to check out Beej's Guide to Sockets Programming:

Since people are still reading this, an additional note:

man (7) ip:

When a process wants to receive new incoming packets or connections, it should bind a socket to a local interface address using bind(2).

In this case, only one IP socket may be bound to any given local (address, port) pair. When INADDR_ANY is specified in the bind call, the socket will be bound to all local interfaces.

When listen(2) is called on an unbound socket, the socket is automatically bound to a random free port with the local address set to INADDR_ANY.

When connect(2) is called on an unbound socket, the socket is automatically bound to a random free port or to a usable shared port with the local address set to INADDR_ANY...

There are several special addresses: INADDR_LOOPBACK ( always refers to the local host via the loopback device; INADDR_ANY ( means any address for binding...


bind() — Bind a name to a socket:

If the (sin_addr.s_addr) field is set to the constant INADDR_ANY, as defined in netinet/in.h, the caller is requesting that the socket be bound to all network interfaces on the host. Subsequently, UDP packets and TCP connections from all interfaces (which match the bound name) are routed to the application. This becomes important when a server offers a service to multiple networks. By leaving the address unspecified, the server can accept all UDP packets and TCP connection requests made for its port, regardless of the network interface on which the requests arrived.

How do I print uint32_t and uint16_t variables value?

You need to include inttypes.h if you want all those nifty new format specifiers for the intN_t types and their brethren, and that is the correct (ie, portable) way to do it, provided your compiler complies with C99. You shouldn't use the standard ones like %d or %u in case the sizes are different to what you think.

It includes stdint.h and extends it with quite a few other things, such as the macros that can be used for the printf/scanf family of calls. This is covered in section 7.8 of the ISO C99 standard.

For example, the following program:

#include <stdio.h>
#include <inttypes.h>
int main (void) {
    uint32_t a=1234;
    uint16_t b=5678;
    printf("%" PRIu32 "\n",a);
    printf("%" PRIu16 "\n",b);
    return 0;



Escape @ character in razor view engine

Razor @ escape char to symbols...

<img src="..." alt="Find me on twitter as @("@username")" />


<img src="..." alt="Find me on twitter as @("@")username" />

How create table only using <div> tag and Css

This is an old thread, but I thought I should post my solution. I faced the same problem recently and the way I solved it is by following a three-step approach as outlined below which is very simple without any complex CSS.

(NOTE : Of course, for modern browsers, using the values of table or table-row or table-cell for display CSS attribute would solve the problem. But the approach I used will work equally well in modern and older browsers since it does not use these values for display CSS attribute.)


For table with divs only so you get cells and rows just like in a table element use the following approach.

  1. Replace table element with a block div (use a .table class)
  2. Replace each tr or th element with a block div (use a .row class)
  3. Replace each td element with an inline block div (use a .cell class)

.table {display:block; }_x000D_
.row { display:block;}_x000D_
.cell {display:inline-block;}
    <h2>Table below using table element</h2>_x000D_
    <table cellspacing="0" >_x000D_
          <td>36 years</td>_x000D_
          <td>45 years</td>_x000D_
          <td>Vice President aas</td>_x000D_
          <td>27 years</td>_x000D_
          <td>Junior Developer</td>_x000D_
    <h2>Table below is using Divs only</h2>_x000D_
    <div class="table">_x000D_
       <div class="row">_x000D_
          <div class="cell">_x000D_
          <div class="cell">_x000D_
             36 years_x000D_
          <div class="cell">_x000D_
       <div class="row">_x000D_
          <div class="cell">_x000D_
          <div class="cell">_x000D_
             45 years_x000D_
          <div class="cell">_x000D_
             Vice President_x000D_
       <div class="row">_x000D_
          <div class="cell">_x000D_
          <div class="cell">_x000D_
             27 years_x000D_
          <div class="cell">_x000D_
             Junior Developer_x000D_


To get around the effect of same width not being maintained across all cells of a column as mentioned by thatslch in a comment, one could adopt either of the two approaches below.

  • Specify a width for cell class

    cell {display:inline-block; width:340px;}

  • Use CSS of modern browsers as below.

    .table {display:table; } .row { display:table-row;} .cell {display:table-cell;}

Multiple conditions in a C 'for' loop

There is an operator in C called the comma operator. It executes each expression in order and returns the value of the last statement. It's also a sequence point, meaning each expression is guaranteed to execute in completely and in order before the next expression in the series executes, similar to && or ||.

Fragments within Fragments

Nested fragments are supported in android 4.2 and later

The Android Support Library also now supports nested fragments, so you can implement nested fragment designs on Android 1.6 and higher.

To nest a fragment, simply call getChildFragmentManager() on the Fragment in which you want to add a fragment. This returns a FragmentManager that you can use like you normally do from the top-level activity to create fragment transactions. For example, here’s some code that adds a fragment from within an existing Fragment class:

Fragment videoFragment = new VideoPlayerFragment();
FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
transaction.add(, videoFragment).commit();

To get more idea about nested fragments, please go through these tutorials
Part 1
Part 2
Part 3

and here is a SO post which discuss about best practices for nested fragments.

Quickest way to compare two generic lists for differences

More efficient would be using Enumerable.Except:

var inListButNotInList2 = list.Except(list2);
var inList2ButNotInList = list2.Except(list);

This method is implemented by using deferred execution. That means you could write for example:

var first10 = inListButNotInList2.Take(10);

It is also efficient since it internally uses a Set<T> to compare the objects. It works by first collecting all distinct values from the second sequence, and then streaming the results of the first, checking that they haven't been seen before.

"Sub or Function not defined" when trying to run a VBA script in Outlook

This probably does not answer your question, but I had the same question and it answered mine.

I changed Private Function to Public Function and it worked.

Remove duplicate elements from array in Ruby

If someone was looking for a way to remove all instances of repeated values, see "How can I efficiently extract repeated elements in a Ruby array?".

a = [1, 2, 2, 3]
counts =
a.each { |v| counts[v] += 1 }
p { |v, count| count == 1 }.keys # [1, 3]

Sql connection-string for localhost server

Do You have Internal Connection or External Connection. If you did Internal Connection then try this:

"Data Source=.\SQLEXPRESS;AttachDbFilename="Your PAth .mdf";Integrated Security=True;User Instance=True";

Should I use past or present tense in git commit messages?

Your project should almost always use the past tense. In any case, the project should always use the same tense for consistency and clarity.

I understand some of the other arguments arguing to use the present tense, but they usually don't apply. The following bullet points are common arguments for writing in the present tense, and my response.

  • Writing in the present tense tells someone what applying the commit will do, rather than what you did.

This is the most correct reason one would want to use the present tense, but only with the right style of project. This manner of thinking considers all commits as optional improvements or features, and you are free to decide which commits to keep and which to reject in your particular repository.

This argument works if you are dealing with a truly distributed project. If you are dealing with a distributed project, you are probably working on an open source project. And it is probably a very large project if it is really distributed. In fact, it's probably either the Linux kernel or Git. Since Linux is likely what caused Git to spread and gain in popularity, it's easy to understand why people would consider its style the authority. Yes, the style makes sense with those two projects. Or, in general, it works with large, open source, distributed projects.

That being said, most projects in source control do not work like this. It is usually incorrect for most repositories. It's a modern way of thinking about a commits: Subversion (SVN) and CVS repositories could barely support this style of repository check-ins. Usually an integration branch handled filtering bad check-ins, but those generally weren't considered "optional" or "nice-to-have features".

In most scenarios, when you are making commits to a source repository, you are writing a journal entry which describes what changed with this update, to make it easier for others in the future to understand why a change was made. It generally isn't an optional change - other people in the project are required to either merge or rebase on it. You don't write a diary entry such as "Dear diary, today I meet a boy and he says hello to me.", but instead you write "I met a boy and he said hello to me."

Finally, for such non-distributed projects, 99.99% of the time a person will be reading a commit message is for reading history - history is read in the past tense. 0.01% of the time it will be deciding whether or not they should apply this commit or integrate it into their branch/repository.

  • Consistency. That's how it is in many projects (including git itself). Also git tools that generate commits (like git merge or git revert) do it.

No, I guarantee you that the majority of projects ever logged in a version control system have had their history in the past tense (I don't have references, but it's probably right, considering the present tense argument is new since Git). "Revision" messages or commit messages in the present tense only started making sense in truly distributed projects - see the first point above.

  • People not only read history to know "what happened to this codebase", but also to answer questions like "what happens when I cherry-pick this commit", or "what kind of new things will happen to my code base because of these commits I may or may not merge in the future".

See the first point. 99.99% of the time a person will be reading a commit message is for reading history - history is read in the past tense. 0.01% of the time it will be deciding whether or not they should apply this commit or integrate it into their branch/repository. 99.99% beats 0.01%.

  • It's usually shorter

I've never seen a good argument that says use improper tense/grammar because it's shorter. You'll probably only save 3 characters on average for a standard 50 character message. That being said, the present tense on average will probably be a few characters shorter.

  • You can name commits more consistently with titles of tickets in your issue/feature tracker (which don't use past tense, although sometimes future)

Tickets are written as either something that is currently happening (e.g. the app is showing the wrong behavior when I click this button), or something that needs to be done in the future (e.g. the text will need a review by the editor).

History (i.e. commit messages) is written as something that was done in the past (e.g. the problem was fixed).

Send array with Ajax to PHP script

 dataString = [];
        type: "POST",
        url: "script.php",
        data:{data: $(dataString).serializeArray()}, 
        cache: false,

        success: function(){

Total size of the contents of all the files in a directory

For Win32 DOS, you can:

c:> dir /s c:\directory\you\want

and the penultimate line will tell you how many bytes the files take up.

I know this reads all files and directories, but works faster in some situations.

DataGridView AutoFit and Fill

Not tested but you can give a try. Tested and working. I hope you can play with AutoSizeMode of DataGridViewColum to achieve what you need.

Try setting

dataGridView1.DataSource = yourdatasource;<--set datasource before you set AutoSizeMode

//Set the following properties after setting datasource
dataGridView1.Columns[0].AutoSizeMode = DataGridViewAutoSizeColumnMode.AllCells;
dataGridView1.Columns[1].AutoSizeMode = DataGridViewAutoSizeColumnMode.AllCells;
dataGridView1.Columns[2].AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill;

This should work

Bootstrap 3 : Vertically Center Navigation Links when Logo Increasing The Height of Navbar

add this to your stylesheet. line-height should match the height of your logo

.navbar-nav li a {
 line-height: 50px;

Check out the fiddle at:

Class file has wrong version 52.0, should be 50.0

i faced the same problem "Class file has wrong version 52.0, should be 50.0" when running java through ant... all i did was add fork="true" wherever i used the javac task and it worked...

Laravel Query Builder where max id

You should be able to perform a select on the orders table, using a raw WHERE to find the max(id) in a subquery, like this:

 \DB::table('orders')->where('id', \DB::raw("(select max(`id`) from orders)"))->get();

If you want to use Eloquent (for example, so you can convert your response to an object) you will want to use whereRaw, because some functions such as toJSON or toArray will not work without using Eloquent models.

 $order = Order::whereRaw('id = (select max(`id`) from orders)')->get();

That, of course, requires that you have a model that extends Eloquent.

 class Order extends Eloquent {}

As mentioned in the comments, you don't need to use whereRaw, you can do the entire query using the query builder without raw SQL.

 // Using the Query Builder

 // Using Eloquent
 $order = Order::find(\DB::table('orders')->max('id'));

(Note that if the id field is not unique, you will only get one row back - this is because find() will only return the first result from the SQL server.).

How to print out a variable in makefile

from a "Mr. Make post"

Add the following rule to your Makefile:

print-%  : ; @echo $* = $($*)

Then, if you want to find out the value of a makefile variable, just:

make print-VARIABLE

and it will return:

VARIABLE = the_value_of_the_variable

How to input automatically when running a shell over SSH?

ssh-key with passphrase, with keychain

keychain is a small utility which manages ssh-agent on your behalf and allows the ssh-agent to remain running when the login session ends. On subsequent logins, keychain will connect to the existing ssh-agent instance. In practice, this means that the passphrase must be be entered only during the first login after a reboot. On subsequent logins, the unencrypted key from the existing ssh-agent instance is used. This can also be useful for allowing passwordless RSA/DSA authentication in cron jobs without passwordless ssh-keys.

To enable keychain, install it and add something like the following to ~/.bash_profile:

eval keychain --agents ssh --eval id_rsa From a security point of view, ssh-ident and keychain are worse than ssh-agent instances limited to the lifetime of a particular session, but they offer a high level of convenience. To improve the security of keychain, some people add the --clear option to their ~/.bash_profile keychain invocation. By doing this passphrases must be re-entered on login as above, but cron jobs will still have access to the unencrypted keys after the user logs out. The keychain wiki page has more information and examples.

Got this info from;

Hope this helps

I have personally been able to automatically enter my passphrase upon terminal launch by doing this: (you can, of course, modify the script and fit it to your needs)

  1. edit the bashrc file to add this script;

    Check if the SSH agent is awake

    if [ -z "$SSH_AUTH_SOCK" ] ; then exec ssh-agent bash -c "ssh-add ; $0" echo "The SSH agent was awakened" exit fi

    Above line will start the expect script upon terminal launch.


here's the content of this expect script


set timeout 20

set passphrase "test"

spawn "./"

expect "Enter passphrase for /the/path/of/yourkey_id_rsa:"

send "$passphrase\r";


Here's the content of my script (you must put both scripts in your home folder, usually /home/user)


ssh-add /the/path/of/yourkey_id_rsa

exit 0

I would HIGHLY suggest encrypting the password on the .exp script as well as renaming this .exp file to something like term_boot.exp or whatever else for security purposes. Don't forget to create the files directly from the terminal using nano or vim (ex: nano ~/.bashrc | nano term_boot.exp) and also a chmod +x to make it executable. A chmod +r term_boot.exp would be also useful but you'll have to add sudo before ./ssh.exp in your bashrc file. So you'll have to enter your sudo password each time you launch your terminal. For me, it's more convenient than the passphrase cause I remember my admin (sudo) password by the hearth.

Also, here's another way to do it I think;

Will certainly change my method for this one when I'll have the time.

Get filename and path from URI from mediastore

Things are complicated now especially after API level 29 Android Q. This is how you should get filename from the content Uri

        public static String getNameFromContentUri(Context context, Uri contentUri){  
                            Cursor returnCursor = context.getContentResolver().query(contentUri, null, null, null, null);
                            int nameColumnIndex = returnCursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
                            String fileName = returnCursor.getString(nameColumnIndex);
                            return fileName;}

and this is how you get full path of the Content Uri for all android versions

public static String getFullPathFromContentUri(final Context context, final Uri uri) {

        final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;

        // DocumentProvider
        if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
            // ExternalStorageProvider
            if ("".equals(uri.getAuthority())) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final String type = split[0];

                if ("primary".equalsIgnoreCase(type)) {
                    return Environment.getExternalStorageDirectory() + "/" + split[1];

                // TODO handle non-primary volumes
            // DownloadsProvider
            else if ("".equals(uri.getAuthority())) {

                final String id = DocumentsContract.getDocumentId(uri);
                final Uri contentUri = ContentUris.withAppendedId(
                        Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

                return getDataColumn(context, contentUri, null, null);
            // MediaProvider
            else if ("".equals(uri.getAuthority())) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final String type = split[0];

                Uri contentUri = null;
                if ("image".equals(type)) {
                    contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
                } else if ("video".equals(type)) {
                    contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
                } else if ("audio".equals(type)) {
                    contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;

                final String selection = "_id=?";
                final String[] selectionArgs = new String[]{

                   Cursor cursor = null;
                   final String column = "_data";
                   final String[] projection = {

        try {
            cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
            if (cursor != null && cursor.moveToFirst()) {
                final int column_index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(column_index);
        } finally {
            if (cursor != null)
        return null;
        // MediaStore (and general)
        else if ("content".equalsIgnoreCase(uri.getScheme())) {
            return getDataColumn(context, uri, null, null);
        // File
        else if ("file".equalsIgnoreCase(uri.getScheme())) {
            return uri.getPath();

        return null;

private static String getDataColumn(Context context, Uri uri, String selection,
                                 String[] selectionArgs) {

        Cursor cursor = null;
        final String column = "_data";
        final String[] projection = {

        try {
            cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
            if (cursor != null && cursor.moveToFirst()) {
                final int column_index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(column_index);
        } finally {
            if (cursor != null)
        return null;

Vagrant ssh authentication failure

I have started the machine, then:

vagrant ssh-config

I've gotten the following:

Host default HostName User vagrant Port 2222 UserKnownHostsFile /dev/null StrictHostKeyChecking no PasswordAuthentication no IdentityFile /Users/my-user-name/Documents/PHP-Projects/my-php-project/puphpet/files/dot/ssh/id_rsa IdentityFile /Users/my-user-name/.vagrant.d/insecure_private_key IdentitiesOnly yes LogLevel FATAL

Then I've ran

cat ~/.ssh/id_rsa > /Users/my-user-name/Documents/PHP-Projects/my-php-project/puphpet/files/dot/ssh/id_rsa

Machine booted from here on

  • El Capitan 10.11.1 Beta (15B38b)
  • Virtual Box 5.0.8 r103449
  • Vagrant 1.7.4

Where can I find a NuGet package for upgrading to System.Web.Http v5.0.0.0?

I have several projects in a solution. For some of the projects, I previously added the references manually. When I used NuGet to update the WebAPI package, those references were not updated automatically.

I found out that I can either manually update those reference so they point to the v5 DLL inside the Packages folder of my solution or do the following.

  1. Go to the "Manage NuGet Packages"
  2. Select the Installed Package "Microsoft ASP.NET Web API 2.1"
  3. Click Manage and check the projects that I manually added before.

MySQL error: key specification without a key length

Also, if you want to use index in this field, you should use the MyISAM storage engine and the FULLTEXT index type.

JPA & Criteria API - Select only specific columns

First of all, I don't really see why you would want an object having only ID and Version, and all other props to be nulls. However, here is some code which will do that for you (which doesn't use JPA Em, but normal Hibernate. I assume you can find the equivalence in JPA or simply obtain the Hibernate Session obj from the em delegate Accessing Hibernate Session from EJB using EntityManager ):

List<T> results = session.createCriteria(entityClazz)
    .setProjection( Projections.projectionList()
        .add( Property.forName("ID") )
        .add( Property.forName("VERSION") )

This will return a list of Objects having their ID and Version set and all other props to null, as the aliasToBean transformer won't be able to find them. Again, I am uncertain I can think of a situation where I would want to do that.

Difference between <context:annotation-config> and <context:component-scan>

<context:component-scan /> implicitly enables <context:annotation-config/>

try with <context:component-scan base-package="..." annotation-config="false"/> , in your configuration @Service, @Repository, @Component works fine, but @Autowired,@Resource and @Inject doesn't work.

This means AutowiredAnnotationBeanPostProcessor will not be enabled and Spring container will not process the Autowiring annotations.

Checking if a list of objects contains a property with a specific value

myList.Where(item=>item.Name == nameToExtract)

Send Post Request with params using Retrofit


      compile ''

      compile 'com.squareup.retrofit2:retrofit:2.1.0'// compulsory

      compile 'com.squareup.retrofit2:converter-gson:2.1.0' //for retrofit conversion

Login APi Put Two Parameters

        "UserId": "1234",

Login Response

        "UserId": "1234",
        "FirstName": "Keshav",
        "LastName": "Gera",
        "ProfilePicture": "312.113.221.1/GEOMVCAPI/Files/1.500534651736E12p.jpg"

    import retrofit2.Retrofit;
    import retrofit2.converter.gson.GsonConverterFactory;

    class APIClient {

        public static final String BASE_URL = "Your Base Url ";
        private static Retrofit retrofit = null;

        public static Retrofit getClient() {
            if (retrofit == null) {
                retrofit = new Retrofit.Builder()
            return retrofit;

APIInterface interface

    interface APIInterface {

        Call<LoginResponse> createUser(@Body LoginResponse login);

Login Pojo

    package pojos;


    public class LoginResponse {

        public String UserId;
        public String FirstName;
        public String LastName;
        public String ProfilePicture;
        public String Password;
        public String ResponseCode;
        public String ResponseMessage;

        public LoginResponse(String UserId, String Password) {
            this.UserId = UserId;
            this.Password = Password;

        public String getUserId() {
            return UserId;

        public String getFirstName() {
            return FirstName;

        public String getLastName() {
            return LastName;

        public String getProfilePicture() {
            return ProfilePicture;

        public String getResponseCode() {
            return ResponseCode;

        public String getResponseMessage() {
            return ResponseMessage;


    package com.keshav.retrofitloginexampleworkingkeshav;

    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.TextView;
    import android.widget.Toast;

    import pojos.LoginResponse;
    import retrofit2.Call;
    import retrofit2.Callback;
    import retrofit2.Response;
    import utilites.CommonMethod;

    public class MainActivity extends AppCompatActivity {

        TextView responseText;
        APIInterface apiInterface;

        Button loginSub;
        EditText et_Email;
        EditText et_Pass;
        private Dialog mDialog;
        String userId;
        String password;

        protected void onCreate(Bundle savedInstanceState) {

            apiInterface = APIClient.getClient().create(APIInterface.class);

            loginSub = (Button) findViewById(;
            et_Email = (EditText) findViewById(;
            et_Pass = (EditText) findViewById(;

            loginSub.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    if (checkValidation()) {
                        if (CommonMethod.isNetworkAvailable(MainActivity.this))
                            loginRetrofit2Api(userId, password);
                            CommonMethod.showAlert("Internet Connectivity Failure", MainActivity.this);

        private void loginRetrofit2Api(String userId, String password) {
            final LoginResponse login = new LoginResponse(userId, password);
            Call<LoginResponse> call1 = apiInterface.createUser(login);
            call1.enqueue(new Callback<LoginResponse>() {
                public void onResponse(Call<LoginResponse> call, Response<LoginResponse> response) {
                    LoginResponse loginResponse = response.body();

                    Log.e("keshav", "loginResponse 1 --> " + loginResponse);
                    if (loginResponse != null) {
                        Log.e("keshav", "getUserId          -->  " + loginResponse.getUserId());
                        Log.e("keshav", "getFirstName       -->  " + loginResponse.getFirstName());
                        Log.e("keshav", "getLastName        -->  " + loginResponse.getLastName());
                        Log.e("keshav", "getProfilePicture  -->  " + loginResponse.getProfilePicture());

                        String responseCode = loginResponse.getResponseCode();
                        Log.e("keshav", "getResponseCode  -->  " + loginResponse.getResponseCode());
                        Log.e("keshav", "getResponseMessage  -->  " + loginResponse.getResponseMessage());
                        if (responseCode != null && responseCode.equals("404")) {
                            Toast.makeText(MainActivity.this, "Invalid Login Details \n Please try again", Toast.LENGTH_SHORT).show();
                        } else {
                            Toast.makeText(MainActivity.this, "Welcome " + loginResponse.getFirstName(), Toast.LENGTH_SHORT).show();

                public void onFailure(Call<LoginResponse> call, Throwable t) {
                    Toast.makeText(getApplicationContext(), "onFailure called ", Toast.LENGTH_SHORT).show();

        public boolean checkValidation() {
            userId = et_Email.getText().toString();
            password = et_Pass.getText().toString();

            Log.e("Keshav", "userId is -> " + userId);
            Log.e("Keshav", "password is -> " + password);

            if (et_Email.getText().toString().trim().equals("")) {
                CommonMethod.showAlert("UserId Cannot be left blank", MainActivity.this);
                return false;
            } else if (et_Pass.getText().toString().trim().equals("")) {
                CommonMethod.showAlert("password Cannot be left blank", MainActivity.this);
                return false;
            return true;

    public class CommonMethod {

        public static final String DISPLAY_MESSAGE_ACTION =

        public static final String EXTRA_MESSAGE = "message";

        public  static boolean isNetworkAvailable(Context ctx) {
            ConnectivityManager connectivityManager
                    = (ConnectivityManager)ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
            return activeNetworkInfo != null && activeNetworkInfo.isConnected();

        public static void showAlert(String message, Activity context) {

            final AlertDialog.Builder builder = new AlertDialog.Builder(context);
                    .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {

            try {
            } catch (Exception e) {



    <LinearLayout android:layout_width="wrap_content"


                android:text="Holostik Track and Trace"
                android:visibility="gone" />


                    android:hint="Login ID"




                    android:singleLine="true" />



                    android:textColor="#ffffff" />    


Random character generator with a range of (A..Z, 0..9) and punctuation

The easiest is to do the following:

  • Create a String alphabet with the chars that you want.
  • Say N = alphabet.length()
  • Then we can ask a java.util.Random for an int x = nextInt(N)
  • alphabet.charAt(x) is a random char from the alphabet

Here's an example:

    final String alphabet = "0123456789ABCDE";
    final int N = alphabet.length();

    Random r = new Random();

    for (int i = 0; i < 50; i++) {

ORA-12560: TNS:protocol adaptor error

It really has worked on my machine. But instead of OracleServiceORCL I found OracleServiceXE.

Timeout on a function call

timeout-decorator don't work on windows system as , windows didn't support signal well.

If you use timeout-decorator in windows system you will get the following

AttributeError: module 'signal' has no attribute 'SIGALRM'

Some suggested to use use_signals=False but didn't worked for me.

Author @bitranox created the following package:

pip install

Code Sample:

import time
from wrapt_timeout_decorator import *

def mytest(message):
    for i in range(1,10):
        print('{} seconds have passed'.format(i))

def main():

if __name__ == '__main__':

Gives the following exception:

TimeoutError: Function mytest timed out after 5 seconds

Make Error 127 when running trying to compile code

Error 127 means one of two things:

  1. file not found: the path you're using is incorrect. double check that the program is actually in your $PATH, or in this case, the relative path is correct -- remember that the current working directory for a random terminal might not be the same for the IDE you're using. it might be better to just use an absolute path instead.
  2. ldso is not found: you're using a pre-compiled binary and it wants an interpreter that isn't on your system. maybe you're using an x86_64 (64-bit) distro, but the prebuilt is for x86 (32-bit). you can determine whether this is the answer by opening a terminal and attempting to execute it directly. or by running file -L on /bin/sh (to get your default/native format) and on the compiler itself (to see what format it is).

if the problem is (2), then you can solve it in a few diff ways:

  1. get a better binary. talk to the vendor that gave you the toolchain and ask them for one that doesn't suck.
  2. see if your distro can install the multilib set of files. most x86_64 64-bit distros allow you to install x86 32-bit libraries in parallel.
  3. build your own cross-compiler using something like crosstool-ng.
  4. you could switch between an x86_64 & x86 install, but that seems a bit drastic ;).

R multiple conditions in if statement

Read this thread R - boolean operators && and ||.

Basically, the & is vectorized, i.e. it acts on each element of the comparison returning a logical array with the same dimension as the input. && is not, returning a single logical.

"Active Directory Users and Computers" MMC snap-in for Windows 7?

RE: enabling features via the command line

Alternatively, you can enable whichever features you're interested in via the Programs and Features control panel

From the download page Per Noalt provided:

Click Start, click Control Panel, and then click Programs.

  1. In the Programs and Features area, click Turn Windows features on or off.

  2. If you are prompted by User Account Control to enable the Windows Features dialog box to open, click Continue.

  3. In the Windows Features dialog box, expand Remote Server Administration Tools.

  4. Select the remote management tools that you want to install.

How to install and run phpize

Under Redhat Enterprise / CentOS, use yum to install the php-devel module:

yum install php-devel

For PHP 7, you need:

yum install php70-php-devel

How can I list ALL grants a user received?

Following query can be used to get all privileges of one user .. Just provide user name in first query and you will get all privileges to that

WITH users AS (SELECT 'SCHEMA_USER' usr FROM dual), Roles AS (SELECT granted_role FROM dba_role_privs rp JOIN users ON rp.GRANTEE = users.usr UNION SELECT granted_role FROM role_role_privs WHERE role IN (SELECT granted_role FROM dba_role_privs rp JOIN users ON rp.GRANTEE = users.usr)), tab_privilage AS (SELECT OWNER, TABLE_NAME, PRIVILEGE FROM role_tab_privs rtp JOIN roles r ON rtp.role = r.granted_role UNION SELECT OWNER, TABLE_NAME, PRIVILEGE FROM Dba_Tab_Privs dtp JOIN Users ON dtp.grantee = users.usr), sys_privileges AS (SELECT privilege FROM dba_sys_privs dsp JOIN users ON dsp.grantee = users.usr) SELECT * FROM tab_privilage ORDER BY owner, table_name --SELECT * FROM sys_privileges

How to implement WiX installer upgrade?

I used this site to help me understand the basics about WiX Upgrade:

Afterwards I created a sample Installer, (installed a test file), then created the Upgrade installer (installed 2 sample test files). This will give you a basic understanding of how the mechanism works.

And as Mike said in the book from Apress, "The Definitive Guide to Windows Installer", it will help you out to understand, but it is not written using WiX.

Another site that was pretty helpful was this one:

How do I convert between big-endian and little-endian values in C++?

Note that, at least for Windows, htonl() is much slower than their intrinsic counterpart _byteswap_ulong(). The former is a DLL library call into ws2_32.dll, the latter is one BSWAP assembly instruction. Therefore, if you are writing some platform-dependent code, prefer using the intrinsics for speed:

#define htonl(x) _byteswap_ulong(x)

This may be especially important for .PNG image processing where all integers are saved in Big Endian with explanation "One can use htonl()..." {to slow down typical Windows programs, if you are not prepared}.

UIImageView aspect fit and center

Updated answer

When I originally answered this question in 2014, there was no requirement to not scale the image up in the case of a small image. (The question was edited in 2015.) If you have such a requirement, you will indeed need to compare the image's size to that of the imageView and use either UIViewContentModeCenter (in the case of an image smaller than the imageView) or UIViewContentModeScaleAspectFit in all other cases.

Original answer

Setting the imageView's contentMode to UIViewContentModeScaleAspectFit was enough for me. It seems to center the images as well. I'm not sure why others are using logic based on the image. See also this question: iOS aspect fit and center

How can I create a dynamic button click event on a dynamic button?

Simply add the eventhandler to the button when creating it.

 button.Click += new EventHandler(this.button_Click);

void button_Click(object sender, System.EventArgs e)
//your stuff...

Copy text from nano editor to shell

M-^ is copy Text. "M" in my environment is "Esc" key ! not "Ctrl"; so I use Esc + 6 to copy that.

[nano help] Escape-key sequences are notated with the Meta (M-) symbol and can be entered using either the Esc, Alt, or Meta key depending on your keyboard setup.

What is the { get; set; } syntax in C#?

It's a so-called auto property, and is essentially a shorthand for the following (similar code will be generated by the compiler):

private string name;
public string Name
    { = value;

Git error: "Please make sure you have the correct access rights and the repository exists"

Adding ssh key worked for me. You can create ssh key with ssh-keygen command on mac. You should be able to see Deploy keys menu on YourRepository>Settings don't forget to check Allow write access option.

deploy keys menu screenshot

Default value in Doctrine

The workaround I used was a LifeCycleCallback. Still waiting to see if there is any more "native" method, for instance @Column(type="string", default="hello default value").

 * @Entity @Table(name="posts") @HasLifeCycleCallbacks
class Post implements Node, \Zend_Acl_Resource_Interface {


 * @PrePersist
function onPrePersist() {
    // set default date
    $this->dtPosted = date('Y-m-d H:m:s');

UICollectionView - Horizontal scroll, horizontal layout?

From @Erik Hunter, I post full code for make horizontal UICollectionView

UICollectionViewFlowLayout *collectionViewFlowLayout = [[UICollectionViewFlowLayout alloc] init];
[collectionViewFlowLayout setScrollDirection:UICollectionViewScrollDirectionHorizontal];
self.myCollectionView.collectionViewLayout = collectionViewFlowLayout;

In Swift

let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .Horizontal
self.myCollectionView.collectionViewLayout = layout

In Swift 3.0

let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
self.myCollectionView.collectionViewLayout = layout

Hope this help

Is there a way to get version from package.json in nodejs code?

You can use ES6 to import package.json to retrieve version number and output the version on console.

import {name as app_name, version as app_version}  from './path/to/package.json';

console.log(`App ---- ${app_name}\nVersion ---- ${app_version}`);

Steps to send a https request to a rest service in Node js

The easiest way is to use the request module.

request('', function (error, response, body) {
  if (!error && response.statusCode == 200) {

What is path of JDK on Mac ?

Which Mac version are you using? try these paths

 /System/Library/Frameworks/JavaVM.framework/ OR

This link might help - How To Set $JAVA_HOME Environment Variable On Mac OS X

Preloading CSS Images

You could use this jQuery plugin waitForImage or you could put you images into an hidden div or (width:0 and height:0) and use onload event on images.

If you only have like 2-3 images you can bind events and trigger them in a chain so after every image you can do some code.

Violation of PRIMARY KEY constraint. Cannot insert duplicate key in object

Not OP's answer but as this was the first question that popped up for me in google, Id also like to add that users searching for this might need to reseed their table, which was the case for me


What is the Ruby <=> (spaceship) operator?

It's a general comparison operator. It returns either a -1, 0, or +1 depending on whether its receiver is less than, equal to, or greater than its argument.

C/C++ switch case with string

If you are after performance and don't want to go through all the if clauses each time if there are many or the need to hash the values, you could send some extra information to the function with the help of enum or just add an enum type to your structure.

git still shows files as modified after adding to .gitignore

To the people who might be searching for this issue still, are looking at this page only.

This will help you remove cached index files, and then only add the ones you need, including changes to your .gitignore file.

1. git rm -r --cached .  
2. git add .
3. git commit -m 'Removing ignored files'

Here is a little bit more info.

  1. This command will remove all cached files from index.
  2. This command will add all files except those which are mentioned in gitignore.
  3. This command will commit your files again and remove the files you want git to ignore, but keep them in your local directory.

Given an array of numbers, return array of products of all other numbers (no division)

A neat solution with O(n) runtime:

  1. For each element calculate the product of all the elements that occur before that and it store in an array "pre".
  2. For each element calculate the product of all the elements that occur after that element and store it in an array "post"
  3. Create a final array "result", for an element i,

    result[i] = pre[i-1]*post[i+1];

Permission denied (publickey,keyboard-interactive)

You need to change the sshd_config file in the remote server (probably in /etc/ssh/sshd_config).


PasswordAuthentication no


PasswordAuthentication yes

And then restart the sshd daemon.

Nullable type as a generic parameter possible?

The shorter way :

public static T ValueOrDefault<T>(this DataRow reader, string columnName) => 
        reader.IsNull(columnName) ? default : (T) reader[columnName];

return 0 for int, and null for int?

tkinter: Open a new window with a button prompt

Here's the nearly shortest possible solution to your question. The solution works in python 3.x. For python 2.x change the import to Tkinter rather than tkinter (the difference being the capitalization):

import tkinter as tk
#import Tkinter as tk  # for python 2
def create_window():
    window = tk.Toplevel(root)

root = tk.Tk()
b = tk.Button(root, text="Create new window", command=create_window)


This is definitely not what I recommend as an example of good coding style, but it illustrates the basic concepts: a button with a command, and a function that creates a window.

What is the logic behind the "using" keyword in C++?

In C++11, the using keyword when used for type alias is identical to typedef.

A typedef-name can also be introduced by an alias-declaration. The identifier following the using keyword becomes a typedef-name and the optional attribute-specifier-seq following the identifier appertains to that typedef-name. It has the same semantics as if it were introduced by the typedef specifier. In particular, it does not define a new type and it shall not appear in the type-id.

Bjarne Stroustrup provides a practical example:

typedef void (*PFD)(double);    // C style typedef to make `PFD` a pointer to a function returning void and accepting double
using PF = void (*)(double);    // `using`-based equivalent of the typedef above
using P = [](double)->void; // using plus suffix return type, syntax error
using P = auto(double)->void // Fixed thanks to DyP

Pre-C++11, the using keyword can bring member functions into scope. In C++11, you can now do this for constructors (another Bjarne Stroustrup example):

class Derived : public Base { 
    using Base::f;    // lift Base's f into Derived's scope -- works in C++98
    void f(char);     // provide a new f 
    void f(int);      // prefer this f to Base::f(int) 

    using Base::Base; // lift Base constructors Derived's scope -- C++11 only
    Derived(char);    // provide a new constructor 
    Derived(int);     // prefer this constructor to Base::Base(int) 
    // ...

Ben Voight provides a pretty good reason behind the rationale of not introducing a new keyword or new syntax. The standard wants to avoid breaking old code as much as possible. This is why in proposal documents you will see sections like Impact on the Standard, Design decisions, and how they might affect older code. There are situations when a proposal seems like a really good idea but might not have traction because it would be too difficult to implement, too confusing, or would contradict old code.

Here is an old paper from 2003 n1449. The rationale seems to be related to templates. Warning: there may be typos due to copying over from PDF.

First let’s consider a toy example:

template <typename T>
class MyAlloc {/*...*/};

template <typename T, class A>
class MyVector {/*...*/};

template <typename T>

struct Vec {
typedef MyVector<T, MyAlloc<T> > type;
Vec<int>::type p; // sample usage

The fundamental problem with this idiom, and the main motivating fact for this proposal, is that the idiom causes the template parameters to appear in non-deducible context. That is, it will not be possible to call the function foo below without explicitly specifying template arguments.

template <typename T> void foo (Vec<T>::type&);

So, the syntax is somewhat ugly. We would rather avoid the nested ::type We’d prefer something like the following:

template <typename T>
using Vec = MyVector<T, MyAlloc<T> >; //defined in section 2 below
Vec<int> p; // sample usage

Note that we specifically avoid the term “typedef template” and introduce the new syntax involving the pair “using” and “=” to help avoid confusion: we are not defining any types here, we are introducing a synonym (i.e. alias) for an abstraction of a type-id (i.e. type expression) involving template parameters. If the template parameters are used in deducible contexts in the type expression then whenever the template alias is used to form a template-id, the values of the corresponding template parameters can be deduced – more on this will follow. In any case, it is now possible to write generic functions which operate on Vec<T> in deducible context, and the syntax is improved as well. For example we could rewrite foo as:

template <typename T> void foo (Vec<T>&);

We underscore here that one of the primary reasons for proposing template aliases was so that argument deduction and the call to foo(p) will succeed.

The follow-up paper n1489 explains why using instead of using typedef:

It has been suggested to (re)use the keyword typedef — as done in the paper [4] — to introduce template aliases:

template<class T> 
    typedef std::vector<T, MyAllocator<T> > Vec;

That notation has the advantage of using a keyword already known to introduce a type alias. However, it also displays several disavantages among which the confusion of using a keyword known to introduce an alias for a type-name in a context where the alias does not designate a type, but a template; Vec is not an alias for a type, and should not be taken for a typedef-name. The name Vec is a name for the family std::vector< [bullet] , MyAllocator< [bullet] > > – where the bullet is a placeholder for a type-name. Consequently we do not propose the “typedef” syntax. On the other hand the sentence

template<class T>
    using Vec = std::vector<T, MyAllocator<T> >;

can be read/interpreted as: from now on, I’ll be using Vec<T> as a synonym for std::vector<T, MyAllocator<T> >. With that reading, the new syntax for aliasing seems reasonably logical.

I think the important distinction is made here, aliases instead of types. Another quote from the same document:

An alias-declaration is a declaration, and not a definition. An alias- declaration introduces a name into a declarative region as an alias for the type designated by the right-hand-side of the declaration. The core of this proposal concerns itself with type name aliases, but the notation can obviously be generalized to provide alternate spellings of namespace-aliasing or naming set of overloaded functions (see ? 2.3 for further discussion). [My note: That section discusses what that syntax can look like and reasons why it isn't part of the proposal.] It may be noted that the grammar production alias-declaration is acceptable anywhere a typedef declaration or a namespace-alias-definition is acceptable.

Summary, for the role of using:

  • template aliases (or template typedefs, the former is preferred namewise)
  • namespace aliases (i.e., namespace PO = boost::program_options and using PO = ... equivalent)
  • the document says A typedef declaration can be viewed as a special case of non-template alias-declaration. It's an aesthetic change, and is considered identical in this case.
  • bringing something into scope (for example, namespace std into the global scope), member functions, inheriting constructors

It cannot be used for:

int i;
using r = i; // compile-error

Instead do:

using r = decltype(i);

Naming a set of overloads.

// bring cos into scope
using std::cos;

// invalid syntax
using std::cos(double);

// not allowed, instead use Bjarne Stroustrup function pointer alias example
using test = std::cos(double);

How to unset (remove) a collection element after fetching it?

If you know the key which you unset then put directly by comma separated

unset($attr['placeholder'], $attr['autocomplete']);

How do I add a custom script to my package.json file that runs a javascript file?


  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build --prod",
    "build_c": "ng build --prod && del \"../../server/front-end/*.*\" /s /q & xcopy /s dist \"../../server/front-end\"",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"

As you can see, the script "build_c" is building the angular application, then deletes all old files from a directory, then finally copies the result build files.

How to make image hover in css?

Exact solution to your problem

You can change the image on hover by using content:url("YOUR-IMAGE-PATH");

For image hover use below line in your css:


and to change the image on hover using the below config inside img:hover:


Popup Message boxes


Here is the code to a method I call whenever I want an information box to pop up, it hogs the screen until it is accepted:

import javax.swing.JOptionPane;

public class ClassNameHere

    public static void infoBox(String infoMessage, String titleBar)
        JOptionPane.showMessageDialog(null, infoMessage, "InfoBox: " + titleBar, JOptionPane.INFORMATION_MESSAGE);

The first JOptionPane parameter (null in this example) is used to align the dialog. null causes it to center itself on the screen, however any java.awt.Component can be specified and the dialog will appear in the center of that Component instead.

I tend to use the titleBar String to describe where in the code the box is being called from, that way if it gets annoying I can easily track down and delete the code responsible for spamming my screen with infoBoxes.

To use this method call:



For a an in depth description of how to use JavaFX dialogs see: JavaFX Dialogs (official) by code.makery. They are much more powerful and flexible than Swing dialogs and capable of far more than just popping up messages.

As above I'll post a small example of how you could use JavaFX dialogs to achieve the same result

import javafx.scene.control.Alert;
import javafx.scene.control.Alert.AlertType;
import javafx.application.Platform;

public class ClassNameHere

    public static void infoBox(String infoMessage, String titleBar)
        /* By specifying a null headerMessage String, we cause the dialog to
           not have a header */
        infoBox(infoMessage, titleBar, null);

    public static void infoBox(String infoMessage, String titleBar, String headerMessage)
        Alert alert = new Alert(AlertType.INFORMATION);

One thing to keep in mind is that JavaFX is a single threaded GUI toolkit, which means this method should be called directly from the JavaFX application thread. If you have another thread doing work, which needs a dialog then see these SO Q&As: JavaFX2: Can I pause a background Task / Service? and Platform.Runlater and Task Javafx.

To use this method call:




What does "|=" mean? (pipe equal operator)

You have already got sufficient answer for your question. But may be my answer help you more about |= kind of binary operators.

I am writing table for bitwise operators:
Following are valid:

Operator   Description                                   Example
|=        bitwise inclusive OR and assignment operator   C |= 2 is same as C = C | 2
^=        bitwise exclusive OR and assignment operator   C ^= 2 is same as C = C ^ 2
&=        Bitwise AND assignment operator                C &= 2 is same as C = C & 2
<<=       Left shift AND assignment operator             C <<= 2 is same as C = C << 2
>>=       Right shift AND assignment operator            C >>= 2 is same as C = C >> 2  

note all operators are binary operators.

Also Note: (for below points I wanted to add my answer)

  • >>> is bitwise operator in Java that is called Unsigned shift
    but >>>= not an operator in Java. >>>= operator

  • ~ is bitwise complement bits, 0 to 1 and 1 to 0 (Unary operator) but ~= not an operator.

  • Additionally, ! Called Logical NOT Operator, but != Checks if the value of two operands are equal or not, if values are not equal then condition becomes true. e.g. (A != B) is true. where as A=!B means if B is true then A become false (and if B is false then A become true).

side note: | is not called pipe, instead its called OR, pipe is shell terminology transfer one process out to next..

What is the purpose of using WHERE 1=1 in SQL statements?

As you said:

if you are adding conditions dynamically you don't have to worry about stripping the initial AND that's the only reason could be, you are right.

How to URL encode in Python 3?

For Python 3 you could try using quote instead of quote_plus:

import urllib.parse




from requests.utils import requote_uri
requote_uri(" abc")



Set Font Color, Font Face and Font Size in PHPExcel

I recommend you start reading the documentation (4.6.18. Formatting cells). When applying a lot of formatting it's better to use applyFromArray() According to the documentation this method is also suppose to be faster when you're setting many style properties. There's an annex where you can find all the possible keys for this function.

This will work for you:

$phpExcel = new PHPExcel();

$styleArray = array(
    'font'  => array(
        'bold'  => true,
        'color' => array('rgb' => 'FF0000'),
        'size'  => 15,
        'name'  => 'Verdana'

$phpExcel->getActiveSheet()->getCell('A1')->setValue('Some text');

To apply font style to complete excel document:

 $styleArray = array(
   'font'  => array(
        'bold'  => true,
        'color' => array('rgb' => 'FF0000'),
        'size'  => 15,
        'name'  => 'Verdana'

Data truncated for column?

In my case it was a table with an ENUM that accepts the days of the week as integers (0 to 6). When inserting the value 0 as an integer I got the error message "Data truncated for column ..." so to fix it I had to cast the integer to a string. So instead of:

$item->day = 0;

I had to do;

$item->day = (string) 0;

It looks silly to cast the zero like that but in my case it was in a Laravel factory, and I had to write it like this:

$factory->define(App\Schedule::class, function (Faker $faker) {
    return [
        'day' => (string) $faker->numberBetween(0, 6),

What is the difference between MySQL, MySQLi and PDO?

mysqli is the enhanced version of mysql.

PDO extension defines a lightweight, consistent interface for accessing databases in PHP. Each database driver that implements the PDO interface can expose database-specific features as regular extension functions.

setBackground vs setBackgroundDrawable (Android)

i know this is an old question but i have a similar situation ,and my solution was

button.setBackgroundResource( R.drawable.ic_button );
Drawable d = button.getBackground();

and then you can play with the "Drawable", applying color filters, etc

How to hide UINavigationBar 1px bottom line

Here's a very simple solution:

self.navigationController.navigationBar.clipsToBounds = YES;

How to get root directory in yii2

Try out this,

My installation is at D:\xampp\htdocs\advanced

\Yii::$app->basePath will give like D:\xampp\htdocs\advanced\backend.

\Yii::$app->request->BaseUrl will give like localhost\advanced\backend\web\

You may store the image using \Yii::$app->basePath and show it using \Yii::$app->request->BaseUrl

"Line contains NULL byte" in CSV reader (Python)

This will tell you what line is the problem.

import csv

lines = []
with open('output.txt','r') as f:
    for line in f.readlines():

with open('corrected.csv','w') as correct:
    writer = csv.writer(correct, dialect = 'excel')
    with open('input.csv', 'r') as mycsv:
        reader = csv.reader(mycsv)
            for i, row in enumerate(reader):
                if row[0] not in lines:
        except csv.Error:
            print('csv choked on line %s' % (i+1))

Perhaps this from daniweb would be helpful:

I'm getting this error when reading from a csv file: "Runtime Error! line contains NULL byte". Any idea about the root cause of this error?


Ok, I got it and thought I'd post the solution. Simply yet caused me grief... Used file was saved in a .xls format instead of a .csv Didn't catch this because the file name itself had the .csv extension while the type was still .xls

How do I deal with corrupted Git object files?

You can use "find" for remove all files in the /objects directory with 0 in size with the command:

find .git/objects/ -size 0 -delete

Backup is recommended.

How to call function of one php file from another php file and pass parameters to it?

files directory:





function sum(a,b){
 return a+b;
function product(a,b){
return a*b;


require_once "functions.php";
echo "sum of two numbers ". sum(4,2);
echo "<br>"; //  create break line
echo "product of two numbers ".product(2,3);

The Output Is :

sum of two numbers 6 product of two numbers 6

Note: don't write public before function. Public, private, these modifiers can only use when you create class.

How do I spool to a CSV formatted file using SQLPLUS?

With newer versions of client tools, there are multiple options to format the query output. The rest is to spool it to a file or save the output as a file depending on the client tool. Here are few of the ways:

  • SQL*Plus

Using the SQL*Plus commands you could format to get your desired output. Use SPOOL to spool the output to a file.

For example,

SQL> SET colsep ,
SQL> SET pagesize 20
SQL> SET trimspool ON
SQL> SET linesize 200
SQL> SELECT * FROM scott.emp;

     EMPNO,ENAME     ,JOB      ,       MGR,HIREDATE ,       SAL,      COMM,    DEPTNO
      7369,SMITH     ,CLERK    ,      7902,17-DEC-80,       800,          ,        20
      7499,ALLEN     ,SALESMAN ,      7698,20-FEB-81,      1600,       300,        30
      7521,WARD      ,SALESMAN ,      7698,22-FEB-81,      1250,       500,        30
      7566,JONES     ,MANAGER  ,      7839,02-APR-81,      2975,          ,        20
      7654,MARTIN    ,SALESMAN ,      7698,28-SEP-81,      1250,      1400,        30
      7698,BLAKE     ,MANAGER  ,      7839,01-MAY-81,      2850,          ,        30
      7782,CLARK     ,MANAGER  ,      7839,09-JUN-81,      2450,          ,        10
      7788,SCOTT     ,ANALYST  ,      7566,09-DEC-82,      3000,          ,        20
      7839,KING      ,PRESIDENT,          ,17-NOV-81,      5000,          ,        10
      7844,TURNER    ,SALESMAN ,      7698,08-SEP-81,      1500,          ,        30
      7876,ADAMS     ,CLERK    ,      7788,12-JAN-83,      1100,          ,        20
      7900,JAMES     ,CLERK    ,      7698,03-DEC-81,       950,          ,        30
      7902,FORD      ,ANALYST  ,      7566,03-DEC-81,      3000,          ,        20
      7934,MILLER    ,CLERK    ,      7782,23-JAN-82,      1300,          ,        10

14 rows selected.

  • SQL Developer Version pre 4.1

Alternatively, you could use the new /*csv*/ hint in SQL Developer.


For example, in my SQL Developer Version

enter image description here

Now you could save the output into a file.

  • SQL Developer Version 4.1

New in SQL Developer version 4.1, use the following just like sqlplus command and run as script. No need of the hint in the query.


Now you could save the output into a file.

Set textarea width to 100% in bootstrap modal

After testing those suggestions here, I draw the conclusion that we have to apply two things.

  1. Apply form-control class to your textarea element. This is among Bootstrap's built-in classes.

  2. Extend this class by adding the following property:

.form-control {
   max-width: 100%;

Hope this helps others who are looking for a solution to this issue.

JVM option -Xss - What does it do exactly?

Each thread in a Java application has its own stack. The stack is used to hold return addresses, function/method call arguments, etc. So if a thread tends to process large structures via recursive algorithms, it may need a large stack for all those return addresses and such. With the Sun JVM, you can set that size via that parameter.

An internal error occurred during: "Updating Maven Project". Unsupported IClasspathEntry kind=4

This issue ( is fixed in m2e 1.5.0 which is available for Eclipse Kepler and Luna from this p2 repo :

If you also use m2e-wtp, you'll need to install m2e-wtp 1.1.0 as well :

How to set image in imageview in android?

use the following code,

    iv.setImageResource(getResources().getIdentifier("apple", "drawable", getPackageName()));

How to get a list of current open windows/process with Java?

On Windows there is an alternative using JNA:

import com.sun.jna.Native;
import com.sun.jna.platform.win32.*;
import com.sun.jna.win32.W32APIOptions;

public class ProcessList {

    public static void main(String[] args) {
        WinNT winNT = (WinNT) Native.loadLibrary(WinNT.class, W32APIOptions.UNICODE_OPTIONS);

        WinNT.HANDLE snapshot = winNT.CreateToolhelp32Snapshot(Tlhelp32.TH32CS_SNAPPROCESS, new WinDef.DWORD(0));

        Tlhelp32.PROCESSENTRY32.ByReference processEntry = new Tlhelp32.PROCESSENTRY32.ByReference();

        while (winNT.Process32Next(snapshot, processEntry)) {
            System.out.println(processEntry.th32ProcessID + "\t" + Native.toString(processEntry.szExeFile));


Find size and free space of the filesystem containing a given file

Checking the disk usage on your Windows PC can be done as follows:

import psutil

fan = psutil.disk_usage(path="C:/")
print("Available: ",
print("Used: ", fan.used/1000000000)
print("Free: ",
print("Percentage Used: ", fan.percent, "%")

Using Docker-Compose, how to execute multiple commands

I was having same problem where I wanted to run my react app on port 3000 and storybook on port 6006 both in the same containers.

I tried to start both as entrypoint commands from Dockerfile as well as using docker-compose command option.

After spending time on this, decided to separate these services into separate containers and it worked like charm

Getting the parent of a directory in Bash

Depending on whether you need absolute paths you may want to take an extra step:

parent=$(dirname "$child")
abs_parent=$(realpath "$parent")

How to select a node of treeview programmatically in c#?

treeViewMain.SelectedNode = treeViewMain.Nodes.Find(searchNode, true)[0];

where searchNode is the name of the node. I'm personally using a combo "Node + Panel" where Node name is Node + and the same tag is also set on panel of choice. With this command + scan of panels by tag i'm usually able to work a treeview+panel full menu set.

JavaScript for handling Tab Key press

Having following html:

<!-- note that not all browsers focus on links when Tab is pressed -->
<a href="">Link</a>

<input type="text" placeholder="Some input" />
<a href="">Another Link</a>


You can get to active link with:

// event listener for keyup
function checkTabPress(e) {
    "use strict";
    // pick passed event or global event object if passed one is empty
    e = e || event;
    var activeElement;
    if (e.keyCode == 9) {
        // Here read the active selected link.
        activeElement = document.activeElement;
        // If HTML element is an anchor <a>
        if (activeElement.tagName.toLowerCase() == 'a')
            // get it's hyperlink

var body = document.querySelector('body');
body.addEventListener('keyup', checkTabPress);

Here is working example.

Select and trigger click event of a radio button in jquery

Switch the order of the code: You're calling the click event before it is attached.

$(document).ready(function() {
      $("#checkbox_div input:radio").click(function() {



      $("input:radio:first").prop("checked", true).trigger("click");


What is python's site-packages directory?

site-packages is just the location where Python installs its modules.

No need to "find it", python knows where to find it by itself, this location is always part of the PYTHONPATH (sys.path).

Programmatically you can find it this way:

import sys
site_packages = next(p for p in sys.path if 'site-packages' in p)
print site_packages


How to create an empty matrix in R?

The default for matrix is to have 1 column. To explicitly have 0 columns, you need to write

matrix(, nrow = 15, ncol = 0)

A better way would be to preallocate the entire matrix and then fill it in

mat <- matrix(, nrow = 15, ncol = n.columns)
for(column in 1:n.columns){
  mat[, column] <- vector

gradlew: Permission Denied

chmod +x gradlew

Just run the above comment. that's all enjoy your coding...

Java 8: Lambda-Streams, Filter by Method with Exception

Keeping this issue in mind I developed a small library for dealing with checked exceptions and lambdas. Custom adapters allow you to integrate with existing functional types:

stream().map(unchecked(URI::new)) //with a static import

SQL Server Express 2008 Install Side-by-side w/ SQL 2005 Express Fails

I'am trying to install SQL SERVER developer 2008 R2 alongside SQL SERVER 2005 EXPRESS,

i went to program features, clicked on unistall SQL SERVER 2005 EXPRESS, and only checked, WORKSTATION COMPONENTS, it unistalled: support files, sql mngmt studio

After that installation of sql 2008 r2 developer went ok....

Hopes this helps somebody

No module named 'openpyxl' - Python 3.4 - Ubuntu

You have to install it explixitly using the python package manager as

  1. pip install openpyxl for Python 2
  2. pip3 install openpyxl for Python 3

How to select a dropdown value in Selenium WebDriver using Java

code to select dropdown using xpath

Select select = new 

code to select particaular option using selectByVisibleText

select.selectByVisibleText(Last 52 Weeks);

PHP error: php_network_getaddresses: getaddrinfo failed: (while getting information from other site.)

It's because you can't resolve the host name Maybe DNS problems, host is unreachable...

try to use IP address instead of host name... ping this host name... nslookup it...

How to get difference between two rows for a column field?

select t1.rowInt,t1.Value,t2.Value-t1.Value as diff
from (select * from myTable) as t1,
     (select * from myTable where rowInt!=1
      union all select top 1 rowInt=COUNT(*)+1,Value=0 from myTable) as t2
where t1.rowInt=t2.rowInt-1

How can I check if a directory exists in a Bash shell script?

Remember to always wrap variables in double quotes when referencing them in a Bash script. Kids these days grow up with the idea that they can have spaces and lots of other funny characters in their directory names. (Spaces! Back in my days, we didn't have no fancy spaces! ;))

One day, one of those kids will run your script with $DIRECTORY set to "My M0viez" and your script will blow up. You don't want that. So use this.

if [ -d "$DIRECTORY" ]; then
    # Will enter here if $DIRECTORY exists, even if it contains spaces

Rest-assured. Is it possible to extract value from request json?

To serialize the response into a class, define the target class

public class Result {
    public Long user_id;

And map response to it:

Response response = given().body(requestBody).when().post("/admin");
Result result =;

You must have Jackson or Gson in the classpath as the documentation states:

Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]

Just go to the project Properties->Project Facets

  1. Uncheck the dynamic module, click apply.

  2. Maven->update the project.

Inline list initialization in VB.NET

Collection initializers are only available in VB.NET 2010, released 2010-04-12:

Dim theVar = New List(Of String) From { "one", "two", "three" }

Change select box option background color

My selects would not color the background until I added !important to the style.

    input, select, select option{background-color:#FFE !important}

Trouble using ROW_NUMBER() OVER (PARTITION BY ...)

It looks like a common gaps-and-islands problem. The difference between two sequences of row numbers rn1 and rn2 give the "group" number.

Run this query CTE-by-CTE and examine intermediate results to see how it works.

Sample data

I expanded sample data from the question a little.

    EmployeeID int,
    DateStarted date,
    DepartmentID int



Query for SQL Server 2008

There is no LEAD function in SQL Server 2008, so I had to use self-join via OUTER APPLY to get the value of the "next" row for the DateEnd.

        ,ROW_NUMBER() OVER (PARTITION BY EmployeeID ORDER BY DateStarted) AS rn1
        ,ROW_NUMBER() OVER (PARTITION BY EmployeeID, DepartmentID ORDER BY DateStarted) AS rn2
    FROM @Source
        ,MIN(DateStarted) AS DateStart
        ,rn1 - rn2
        SELECT TOP(1) G2.DateStart AS DateEnd
        FROM CTE_Groups AS G2
            G2.EmployeeID = CTE_Groups.EmployeeID
            AND G2.DateStart > CTE_Groups.DateStart
        ORDER BY G2.DateStart
    ) AS A

Query for SQL Server 2012+

Starting with SQL Server 2012 there is a LEAD function that makes this task more efficient.

        ,ROW_NUMBER() OVER (PARTITION BY EmployeeID ORDER BY DateStarted) AS rn1
        ,ROW_NUMBER() OVER (PARTITION BY EmployeeID, DepartmentID ORDER BY DateStarted) AS rn2
    FROM @Source
        ,MIN(DateStarted) AS DateStart
        ,rn1 - rn2
    ,LEAD(CTE_Groups.DateStart) OVER (PARTITION BY CTE_Groups.EmployeeID ORDER BY CTE_Groups.DateStart) AS DateEnd


| EmployeeID | DepartmentID | DateStart  |  DateEnd   |
|      10001 |            1 | 2013-01-01 | 2013-12-01 |
|      10001 |            2 | 2013-12-01 | 2014-10-01 |
|      10001 |            1 | 2014-10-01 | NULL       |
|      10005 |            1 | 2013-05-01 | 2013-12-01 |
|      10005 |            2 | 2013-12-01 | 2014-10-01 |
|      10005 |            1 | 2014-10-01 | NULL       |

How to read response headers in angularjs?

According the MDN custom headers are not exposed by default. The server admin need to expose them using "Access-Control-Expose-Headers" in the same fashion they deal with "access-control-allow-origin"

See this MDN link for confirmation []

How to put data containing double-quotes in string variable?

You can escape (this is how this principle is called) the double quotes by prefixing them with another double quote. You can put them in a string as follows:

Dim MyVar as string = "some text ""hello"" "

This will give the MyVar variable a value of some text "hello".

How to Detect Browser Window /Tab Close Event?

This code prevents the checkbox events. It works when user clicks on browser close button but it doesn't work when checkbox clicked. You can modify it for other controls(texbox, radiobutton etc.)

    window.onbeforeunload = function () {
        return "Are you sure?";

    $(function () {
        $('input[type="checkbox"]').click(function () {
            window.onbeforeunload = function () { };

SPA best practices for authentication and session management

This question has been addressed, in a slightly different form, at length, here:

RESTful Authentication

But this addresses it from the server-side. Let's look at this from the client-side. Before we do that, though, there's an important prelude:

Javascript Crypto is Hopeless

Matasano's article on this is famous, but the lessons contained therein are pretty important:

To summarize:

  • A man-in-the-middle attack can trivially replace your crypto code with <script> function hash_algorithm(password){ lol_nope_send_it_to_me_instead(password); }</script>
  • A man-in-the-middle attack is trivial against a page that serves any resource over a non-SSL connection.
  • Once you have SSL, you're using real crypto anyways.

And to add a corollary of my own:

  • A successful XSS attack can result in an attacker executing code on your client's browser, even if you're using SSL - so even if you've got every hatch battened down, your browser crypto can still fail if your attacker finds a way to execute any javascript code on someone else's browser.

This renders a lot of RESTful authentication schemes impossible or silly if you're intending to use a JavaScript client. Let's look!

HTTP Basic Auth

First and foremost, HTTP Basic Auth. The simplest of schemes: simply pass a name and password with every request.

This, of course, absolutely requires SSL, because you're passing a Base64 (reversibly) encoded name and password with every request. Anybody listening on the line could extract username and password trivially. Most of the "Basic Auth is insecure" arguments come from a place of "Basic Auth over HTTP" which is an awful idea.

The browser provides baked-in HTTP Basic Auth support, but it is ugly as sin and you probably shouldn't use it for your app. The alternative, though, is to stash username and password in JavaScript.

This is the most RESTful solution. The server requires no knowledge of state whatsoever and authenticates every individual interaction with the user. Some REST enthusiasts (mostly strawmen) insist that maintaining any sort of state is heresy and will froth at the mouth if you think of any other authentication method. There are theoretical benefits to this sort of standards-compliance - it's supported by Apache out of the box - you could store your objects as files in folders protected by .htaccess files if your heart desired!

The problem? You are caching on the client-side a username and password. This gives a better crack at it - even the most basic of XSS vulnerabilities could result in the client beaming his username and password to an evil server. You could try to alleviate this risk by hashing and salting the password, but remember: JavaScript Crypto is Hopeless. You could alleviate this risk by leaving it up to the Browser's Basic Auth support, but.. ugly as sin, as mentioned earlier.

HTTP Digest Auth

Is Digest authentication possible with jQuery?

A more "secure" auth, this is a request/response hash challenge. Except JavaScript Crypto is Hopeless, so it only works over SSL and you still have to cache the username and password on the client side, making it more complicated than HTTP Basic Auth but no more secure.

Query Authentication with Additional Signature Parameters.

Another more "secure" auth, where you encrypt your parameters with nonce and timing data (to protect against repeat and timing attacks) and send the. One of the best examples of this is the OAuth 1.0 protocol, which is, as far as I know, a pretty stonking way to implement authentication on a REST server.

Oh, but there aren't any OAuth 1.0 clients for JavaScript. Why?

JavaScript Crypto is Hopeless, remember. JavaScript can't participate in OAuth 1.0 without SSL, and you still have to store the client's username and password locally - which puts this in the same category as Digest Auth - it's more complicated than HTTP Basic Auth but it's no more secure.


The user sends a username and password, and in exchange gets a token that can be used to authenticate requests.

This is marginally more secure than HTTP Basic Auth, because as soon as the username/password transaction is complete you can discard the sensitive data. It's also less RESTful, as tokens constitute "state" and make the server implementation more complicated.

SSL Still

The rub though, is that you still have to send that initial username and password to get a token. Sensitive information still touches your compromisable JavaScript.

To protect your user's credentials, you still need to keep attackers out of your JavaScript, and you still need to send a username and password over the wire. SSL Required.

Token Expiry

It's common to enforce token policies like "hey, when this token has been around too long, discard it and make the user authenticate again." or "I'm pretty sure that the only IP address allowed to use this token is XXX.XXX.XXX.XXX". Many of these policies are pretty good ideas.


However, using a token Without SSL is still vulnerable to an attack called 'sidejacking':

The attacker doesn't get your user's credentials, but they can still pretend to be your user, which can be pretty bad.

tl;dr: Sending unencrypted tokens over the wire means that attackers can easily nab those tokens and pretend to be your user. FireSheep is a program that makes this very easy.

A Separate, More Secure Zone

The larger the application that you're running, the harder it is to absolutely ensure that they won't be able to inject some code that changes how you process sensitive data. Do you absolutely trust your CDN? Your advertisers? Your own code base?

Common for credit card details and less common for username and password - some implementers keep 'sensitive data entry' on a separate page from the rest of their application, a page that can be tightly controlled and locked down as best as possible, preferably one that is difficult to phish users with.

Cookie (just means Token)

It is possible (and common) to put the authentication token in a cookie. This doesn't change any of the properties of auth with the token, it's more of a convenience thing. All of the previous arguments still apply.

Session (still just means Token)

Session Auth is just Token authentication, but with a few differences that make it seem like a slightly different thing:

  • Users start with an unauthenticated token.
  • The backend maintains a 'state' object that is tied to a user's token.
  • The token is provided in a cookie.
  • The application environment abstracts the details away from you.

Aside from that, though, it's no different from Token Auth, really.

This wanders even further from a RESTful implementation - with state objects you're going further and further down the path of plain ol' RPC on a stateful server.

OAuth 2.0

OAuth 2.0 looks at the problem of "How does Software A give Software B access to User X's data without Software B having access to User X's login credentials."

The implementation is very much just a standard way for a user to get a token, and then for a third party service to go "yep, this user and this token match, and you can get some of their data from us now."

Fundamentally, though, OAuth 2.0 is just a token protocol. It exhibits the same properties as other token protocols - you still need SSL to protect those tokens - it just changes up how those tokens are generated.

There are two ways that OAuth 2.0 can help you:

  • Providing Authentication/Information to Others
  • Getting Authentication/Information from Others

But when it comes down to it, you're just... using tokens.

Back to your question

So, the question that you're asking is "should I store my token in a cookie and have my environment's automatic session management take care of the details, or should I store my token in Javascript and handle those details myself?"

And the answer is: do whatever makes you happy.

The thing about automatic session management, though, is that there's a lot of magic happening behind the scenes for you. Often it's nicer to be in control of those details yourself.

I am 21 so SSL is yes

The other answer is: Use https for everything or brigands will steal your users' passwords and tokens.

MongoDB: Combine data from multiple collections into

Although you can't do this real-time, you can run map-reduce multiple times to merge data together by using the "reduce" out option in MongoDB 1.8+ map/reduce (see You need to have some key in both collections that you can use as an _id.

For example, let's say you have a users collection and a comments collection and you want to have a new collection that has some user demographic info for each comment.

Let's say the users collection has the following fields:

  • _id
  • firstName
  • lastName
  • country
  • gender
  • age

And then the comments collection has the following fields:

  • _id
  • userId
  • comment
  • created

You would do this map/reduce:

var mapUsers, mapComments, reduce;

// setup sample data - wouldn't actually use this in production
var users = db.users.find();{userId: users[0]._id, "comment": "Hey, what's up?", created: new ISODate()});{userId: users[1]._id, "comment": "Not much", created: new ISODate()});{userId: users[0]._id, "comment": "Cool", created: new ISODate()});
// end sample data setup

mapUsers = function() {
    var values = {
        gender: this.gender,
        age: this.age
    emit(this._id, values);
mapComments = function() {
    var values = {
        commentId: this._id,
        comment: this.comment,
        created: this.created
    emit(this.userId, values);
reduce = function(k, values) {
    var result = {}, commentFields = {
        "commentId": '', 
        "comment": '',
        "created": ''
    values.forEach(function(value) {
        var field;
        if ("comment" in value) {
            if (!("comments" in result)) {
                result.comments = [];
        } else if ("comments" in value) {
            if (!("comments" in result)) {
                result.comments = [];
            result.comments.push.apply(result.comments, value.comments);
        for (field in value) {
            if (value.hasOwnProperty(field) && !(field in commentFields)) {
                result[field] = value[field];
    return result;
db.users.mapReduce(mapUsers, reduce, {"out": {"reduce": "users_comments"}});
db.comments.mapReduce(mapComments, reduce, {"out": {"reduce": "users_comments"}});
db.users_comments.find().pretty(); // see the resulting collection

At this point, you will have a new collection called users_comments that contains the merged data and you can now use that. These reduced collections all have _id which is the key you were emitting in your map functions and then all of the values are a sub-object inside the value key - the values aren't at the top level of these reduced documents.

This is a somewhat simple example. You can repeat this with more collections as much as you want to keep building up the reduced collection. You could also do summaries and aggregations of data in the process. Likely you would define more than one reduce function as the logic for aggregating and preserving existing fields gets more complex.

You'll also note that there is now one document for each user with all of that user's comments in an array. If we were merging data that has a one-to-one relationship rather than one-to-many, it would be flat and you could simply use a reduce function like this:

reduce = function(k, values) {
    var result = {};
    values.forEach(function(value) {
        var field;
        for (field in value) {
            if (value.hasOwnProperty(field)) {
                result[field] = value[field];
    return result;

If you want to flatten the users_comments collection so it's one document per comment, additionally run this:

var map, reduce;
map = function() {
    var debug = function(value) {
        var field;
        for (field in value) {
            print(field + ": " + value[field]);
    var that = this;
    if ("comments" in this.value) {
        this.value.comments.forEach(function(value) {
            emit(value.commentId, {
                userId: that._id,
                age: that.value.age,
                comment: value.comment,
                created: value.created,
reduce = function(k, values) {
    var result = {};
    values.forEach(function(value) {
        var field;
        for (field in value) {
            if (value.hasOwnProperty(field)) {
                result[field] = value[field];
    return result;
db.users_comments.mapReduce(map, reduce, {"out": "comments_with_demographics"});

This technique should definitely not be performed on the fly. It's suited for a cron job or something like that which updates the merged data periodically. You'll probably want to run ensureIndex on the new collection to make sure queries you perform against it run quickly (keep in mind that your data is still inside a value key, so if you were to index comments_with_demographics on the comment created time, it would be db.comments_with_demographics.ensureIndex({"value.created": 1});

jQuery: If this HREF contains

use this

$("a").each(function () {
    var href=$(this).prop('href');
    if (href.indexOf('?') > -1) {
        alert("Contains questionmark");

How do I view Android application specific cache?

Here is the code: replace package_name by your specific package name.

Intent i = new Intent(android.provider.Settings.ACTION_APPLICATION_DETAILS_SETTINGS);

Good tool to visualise database schema?

Have you tried the arrange > auto arrange function in MySQL Workbench. It may save you from manually moving the tables around.


I was using


and found that it was giving wrong results (By wrong I mean no results). As there was a NULL in TABLE2.Col1.

While changing the query to


gave me the correct results.

Since then I have started using NOT EXISTS every where.

How do I run Selenium in Xvfb?

The easiest way is probably to use xvfb-run:

DISPLAY=:1 xvfb-run java -jar selenium-server-standalone-2.0b3.jar

xvfb-run does the whole X authority dance for you, give it a try!

How to get city name from latitude and longitude coordinates in Google Maps?

I´m in Brazil. Because of the regional details sometimes the city cames in differents ways. I think its the same in India and other countries. So, to prevent errors I make this verification:

private fun getAddress(latLng: LatLng): String {
    // 1
    val geocoder = Geocoder(this)
    val addresses: List<Address>?
    var city = "no"

    try {

        addresses = geocoder.getFromLocation(latLng.latitude, latLng.longitude, 1)

        if (null != addresses && !addresses.isEmpty()) { //prevent from error
             //sometimes the city comes in locality, sometimes in subAdminArea.
            if (addresses[0].locality == null) {

                city = addresses[0].subAdminArea
            } else {
                city = addresses[0].locality

    } catch (e: IOException) {
        Log.e("MapsActivity", e.localizedMessage)

    return city

You can also check if city returns "no". If so, wasn´t possible to get the user location. Hope it helps.

JavaScript Infinitely Looping slideshow with delays?

try this:

window.onload = function start() {
function slide() {

setInterval is basically an 'infinite loop' and it wont black up the browser. it waits the required time, then goes again

Exception in thread "main" java.lang.UnsupportedClassVersionError: a (Unsupported major.minor version 51.0)

Try sudo update-alternatives --config java from the command line to set the version of the JRE you want to use. This should fix it.

Entitlements file do not match those specified in your provisioning profile.(0xE8008016)

For me, it was an inconsistency between Debug profile (it was automatic) and Release profile (it was manual). Setting them both automatic/manual resolved the issue.

Calling @Html.Partial to display a partial view belonging to a different controller

That's no problem.

@Html.Partial("../Controller/View", model)


@Html.Partial("~/Views/Controller/View.cshtml", model)

Should do the trick.

If you want to pass through the (other) controller, you can use:

@Html.Action("action", "controller", parameters)

or any of the other overloads

How to scroll table's "tbody" independent of "thead"?

try this.

    background-color: #aaa;

    background-color: #ddd;
    height: 100px;
    overflow-y: scroll;
    position: absolute;

    padding: 3px 10px;
    color: green;
    width: 100px;

C++ printing boolean, what is displayed?

The standard streams have a boolalpha flag that determines what gets displayed -- when it's false, they'll display as 0 and 1. When it's true, they'll display as false and true.

There's also an std::boolalpha manipulator to set the flag, so this:

#include <iostream>
#include <iomanip>

int main() {
    std::cout << std::boolalpha;   
    return 0;

...produces output like:


For what it's worth, the actual word produced when boolalpha is set to true is localized--that is, <locale> has a num_put category that handles numeric conversions, so if you imbue a stream with the right locale, it can/will print out true and false as they're represented in that locale. For example,

#include <iostream>
#include <iomanip>
#include <locale>

int main() {

    std::cout << false << "\n";
    std::cout << std::boolalpha;
    std::cout << false << "\n";
    return 0;

...and at least in theory (assuming your compiler/standard library accept "fr" as an identifier for "French") it might print out faux instead of false. I should add, however, that real support for this is uneven at best--even the Dinkumware/Microsoft library (usually quite good in this respect) prints false for every language I've checked.

The names that get used are defined in a numpunct facet though, so if you really want them to print out correctly for particular language, you can create a numpunct facet to do that. For example, one that (I believe) is at least reasonably accurate for French would look like this:

#include <array>
#include <string>
#include <locale>
#include <ios>
#include <iostream>

class my_fr : public std::numpunct< char > {
    char do_decimal_point() const { return ','; }
    char do_thousands_sep() const { return '.'; }
    std::string do_grouping() const { return "\3"; }
    std::string do_truename() const { return "vrai";  }
    std::string do_falsename() const { return "faux"; }

int main() {
    std::cout.imbue(std::locale(std::locale(), new my_fr));

    std::cout << false << "\n";
    std::cout << std::boolalpha;
    std::cout << false << "\n";
    return 0;

And the result is (as you'd probably expect):


How to display raw html code in PRE or something like it but without escaping it

Cheap and cheerful answer:

<textarea>Some raw content</textarea>

The textarea will handle tabs, multiple spaces, newlines, line wrapping all verbatim. It copies and pastes nicely and its valid HTML all the way. It also allows the user to resize the code box. You don't need any CSS, JS, escaping, encoding.

You can alter the appearance and behaviour as well. Here's a monospace font, editing disabled, smaller font, no border:

    style="width:100%; font-family: Monospace; font-size:10px; border:0;"
    rows="30" disabled
>Some raw content</textarea>

This solution is probably not semantically correct. So if you need that, it might be best to choose a more sophisticated answer.

How to get Python requests to trust a self signed SSL certificate?

Case where multiple certificates are needed was solved as follows: Concatenate the multiple root pem files, myCert-A-Root.pem and myCert-B-Root.pem, to a file. Then set the requests REQUESTS_CA_BUNDLE var to that file in my ./.bash_profile.

$ cp myCert-A-Root.pem ca_roots.pem
$ cat myCert-B-Root.pem >> ca_roots.pem
$ echo "export REQUESTS_CA_BUNDLE=~/PATH_TO/CA_CHAIN/ca_roots.pem" >> ~/.bash_profile ; source ~/.bash_profile

How To Execute SSH Commands Via PHP

//Update 2018, works//


Download phpseclib v1 and use this code:

set_include_path(__DIR__ . '/phpseclib1.0.11');

$key ="MyPassword";
  /* ### if using PrivateKey ### 
  $key = new Crypt_RSA();

$ssh = new Net_SSH2('', 22);   // Domain or IP
if (!$ssh->login('your_username', $key))  exit('Login Failed');

echo $ssh->exec('pwd');

or Method2:

Download newest phpseclib v2 (requires composer install at first):


set_include_path($path=__DIR__ . '/phpseclib-master/phpseclib');
include ($path.'/../vendor/autoload.php');

$loader = new \Composer\Autoload\ClassLoader();

use phpseclib\Net\SSH2;

$key ="MyPassword";
  /* ### if using PrivateKey ### 
  use phpseclib\Crypt\RSA;
  $key = new RSA();

$ssh = new SSH2('', 22);   // Domain or IP
if (!$ssh->login('your_username', $key))   exit('Login Failed'); 

echo $ssh->exec('pwd');

p.s. if you get "Connection timed out" then it's probably the issue of HOST/FIREWALL (local or remote) or like that, not a fault of script.

Getting the thread ID from a thread

You can use the deprecated AppDomain.GetCurrentThreadId to get the ID of the currently running thread. This method uses a PInvoke to the Win32 API method GetCurrentThreadID, and will return the Windows thread ID.

This method is marked as deprecated because the .NET Thread object does not correspond to a single Windows thread, and as such there is no stable ID which can be returned by Windows for a given .NET thread.

See configurator's answer for more reasons why this is the case.

Check if String contains only letters

Faster way is below. Considering letters are only a-z,A-Z.

public static void main( String[] args ){ 


    public static boolean bettertWay(String name) {
        char[] chars = name.toCharArray();
        long startTimeOne = System.nanoTime();
        for(char c : chars){
            if(!(c>=65 && c<=90)&&!(c>=97 && c<=122) ){
                System.out.println(System.nanoTime() - startTimeOne);
                    return false;
        System.out.println(System.nanoTime() - startTimeOne);
        return true;

    public static boolean isAlpha(String name) {
        char[] chars = name.toCharArray();
        long startTimeOne = System.nanoTime();
        for (char c : chars) {
            if(!Character.isLetter(c)) {
                System.out.println(System.nanoTime() - startTimeOne);
                return false;
        System.out.println(System.nanoTime() - startTimeOne);
        return true;

Runtime is calculated in nano seconds. It may vary system to system.

5748//bettertWay without numbers
89493 //isAlpha without  numbers
3284 //bettertWay with numbers
22989 //isAlpha with numbers

StringUtils.isBlank() vs String.isEmpty()

StringUtils isEmpty = String isEmpty checks + checks for null.

StringUtils isBlank = StringUtils isEmpty checks + checks if the text contains only whitespace character(s).

Useful links for further investigation:

CSS: stretching background image to 100% width and height of screen?

I would recommend background-size: cover; if you don't want your background to lose its proportions: JS Fiddle

html { 
  background: url(image/path) no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;


Stored Procedure error ORA-06550

create or replace procedure point_triangle

dbms_output.put_line(thisteam.FIRSTNAME|| ' ' || thisteam.LASTNAME || ':' || thisteam.PTS);


Parse JSON with R

For the record, rjson and RJSONIO do change the file type, but they don't really parse per se. For instance, I receive ugly MongoDB data in JSON format, convert it with rjson or RJSONIO, then use unlist and tons of manual correction to actually parse it into a usable matrix.

jQuery - Disable Form Fields

$('input, select').attr('disabled', 'disabled');

How do I set default terminal to terminator?

The only way that worked for me was

  1. Open nautilus or nemo as root user gksudo nautilus
  2. Go to /usr/bin
  3. Change name of your default terminal to any other name for exemple "orig_gnome-terminal"
  4. rename your favorite terminal as "gnome-terminal"

How to execute a stored procedure within C# program

SqlConnection conn = null;
SqlDataReader rdr  = null;
conn = new SqlConnection("Server=(local);DataBase=Northwind;Integrated Security=SSPI");

// 1.  create a command object identifying
//     the stored procedure
SqlCommand cmd  = new SqlCommand("CustOrderHist", conn);

// 2. set the command object so it knows
//    to execute a stored procedure
cmd.CommandType = CommandType.StoredProcedure;

// 3. add parameter to command, which
//    will be passed to the stored procedure
cmd.Parameters.Add(new SqlParameter("@CustomerID", custId));

// execute the command
rdr = cmd.ExecuteReader();

// iterate through results, printing each to console
while (rdr.Read())
    Console.WriteLine("Product: {0,-35} Total: {1,2}", rdr["ProductName"], rdr["Total"]);

Generating random number between 1 and 10 in Bash Shell Script

Simplest solution would be to use tool which allows you to directly specify ranges, like shuf

shuf -i1-10 -n1

If you want to use $RANDOM, it would be more precise to throw out the last 8 numbers in 0...32767, and just treat it as 0...32759, since taking 0...32767 mod 10 you get the following distribution

0-8 each: 3277 
8-9 each: 3276

So, slightly slower but more precise would be

while :; do ran=$RANDOM; ((ran < 32760)) && echo $(((ran%10)+1)) && break; done 

Android - Start service on boot

Looks very similar to mine but I use the full package name for the receiver:

<receiver android:name=".StartupIntentReceiver">

I have:

<receiver android:name="com.your.package.AutoStart"> 

How to output only captured groups with sed?


sed -n -e "/[0-9]/s/^[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\).*$/\1 \2 \3 \4 \5 \6 \7 \8 \9/p"

I got this under cygwin:

$ (echo "asdf"; \
   echo "1234"; \
   echo "asdf1234adsf1234asdf"; \
   echo "1m2m3m4m5m6m7m8m9m0m1m2m3m4m5m6m7m8m9") | \
  sed -n -e "/[0-9]/s/^[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\)[^0-9]*\([0-9]*\).*$/\1 \2 \3 \4 \5 \6 \7 \8 \9/p"

1234 1234
1 2 3 4 5 6 7 8 9

Time part of a DateTime Field in SQL

select cast(getdate() as time(0))

returns for example :- 15:19:43

replace getdate() with the date time you want to extract just time from!

xsd:boolean element type accept "true" but not "True". How can I make it accept it?

If you're on Linux, or have cygwin available on Windows, you can run the input XML through a simple sed script that will replace <Active>True</Active> with <Active>true</Active>, like so:

cat <your XML file> | sed 'sX<Active>True</Active>X<Active>true</Active>X' | xmllint --schema -

If you're not, you can still use a non-validating xslt pocessor (xalan, saxon etc.) to run a simple xslt transformation on the input, and only then pipe it to xmllint.

What the xsl should contain something like below, for the example you listed above (the xslt processor should be 2.0 capable):

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="" version="2.0">
    <xsl:output method="xml" indent="yes"/>
    <xsl:template match="/">
    <xsl:for-each select="XML">
        <xsl:for-each select="Active">
            <xsl:value-of select=" replace(current(), 'True','true')"/>

How to read values from properties file?

You need to put a PropertyPlaceholderConfigurer bean in your application context and set its location property.

See details here :

You might have to modify your property file a bit for this thing to work.

Hope it helps.

Using GSON to parse a JSON array

Wrapper[] data = gson.fromJson(jElement, Wrapper[].class);


This is more of an example where TABLOCK did not work for me and TABLOCKX did.

I have 2 sessions, that both use the default (READ COMMITTED) isolation level:

Session 1 is an explicit transaction that will copy data from a linked server to a set of tables in a database, and takes a few seconds to run. [Example, it deletes Questions] Session 2 is an insert statement, that simply inserts rows into a table that Session 1 doesn't make changes to. [Example, it inserts Answers].

(In practice there are multiple sessions inserting multiple records into the table, simultaneously, while Session 1 is running its transaction).

Session 1 has to query the table Session 2 inserts into because it can't delete records that depend on entries that were added by Session 2. [Example: Delete questions that have not been answered].

So, while Session 1 is executing and Session 2 tries to insert, Session 2 loses in a deadlock every time.

So, a delete statement in Session 1 might look something like this: DELETE tblA FROM tblQ LEFT JOIN tblX on ... LEFT JOIN tblA a ON tblQ.Qid = tblA.Qid WHERE ... a.QId IS NULL and ...

The deadlock seems to be caused from contention between querying tblA while Session 2, [3, 4, 5, ..., n] try to insert into tblA.

In my case I could change the isolation level of Session 1's transaction to be SERIALIZABLE. When I did this: The transaction manager has disabled its support for remote/network transactions.

So, I could follow instructions in the accepted answer here to get around it: The transaction manager has disabled its support for remote/network transactions

But a) I wasn't comfortable with changing the isolation level to SERIALIZABLE in the first place- supposedly it degrades performance and may have other consequences I haven't considered, b) didn't understand why doing this suddenly caused the transaction to have a problem working across linked servers, and c) don't know what possible holes I might be opening up by enabling network access.

There seemed to be just 6 queries within a very large transaction that are causing the trouble.

So, I read about TABLOCK and TabLOCKX.

I wasn't crystal clear on the differences, and didn't know if either would work. But it seemed like it would. First I tried TABLOCK and it didn't seem to make any difference. The competing sessions generated the same deadlocks. Then I tried TABLOCKX, and no more deadlocks.

So, in six places, all I needed to do was add a WITH (TABLOCKX).

So, a delete statement in Session 1 might look something like this: DELETE tblA FROM tblQ q LEFT JOIN tblX x on ... LEFT JOIN tblA a WITH (TABLOCKX) ON tblQ.Qid = tblA.Qid WHERE ... a.QId IS NULL and ...

pypi UserWarning: Unknown distribution option: 'install_requires'

ATTENTION! ATTENTION! Imperfect answer ahead. To get the "latest memo" on the state of packaging in the Python universe, read this fairly detailed essay.

I have just ran into this problem when trying to build/install ansible. The problem seems to be that distutils really doesn't support install_requires. Setuptools should monkey-patch distutils on-the-fly, but it doesn't, probably because the last release of setuptools is 0.6c11 from 2009, whereas distutils is a core Python project.

So even after manually installing the setuptools-0.6c11-py2.7.egg running only picks up distutils, and not the one from site-packages/setuptools/.

Also the setuptools documentation hints to using ez_setup and not distutils.

However, setuptools is itself provided by distribute nowadays, and that flavor of setup() supports install_requires.

Convert from to JodaTime

Each datetime class provides a variety of constructors. These include the Object constructor. This allows you to construct, for example, DateTime from the following objects:

* Date - a JDK instant
* Calendar - a JDK calendar
* String - in ISO8601 format
* Long - in milliseconds
* any Joda-Time datetime class

Node package ( Grunt ) installed but not available

  1. Instala grunt de manera global: sudo npm install -g grunt-cli --unsafe-perm=true --allow-root

  2. Try to run grunt.

  3. If you have this message:


You need to have Ruby and Sass installed and in your PATH for this task to work.

More info:

Used --force, continuing.

3.1. Check that you have ruby installed (mac, you should have it): ruby -v

Cannot open Windows.h in Microsoft Visual Studio

For my case, I had to right click the solution and click "Retarget Projects". In my case I retargetted to Windows SDK version 10.0.1777.0 and Platform Toolset v142. I also had to change "Windows.h"to<windows.h>

I am running Visual Studio 2019 version 16.25 on a windows 10 machine

How do I get the height and width of the Android Navigation Bar programmatically?

The height of the bottom Navigation bar is 48dp (in both portrait and landscape mode) and is 42dp when the bar is placed vertically.

How to print React component on click of a button?

There is kind of two solutions on the client. One is with frames like you posted. You can use an iframe though:

var content = document.getElementById("divcontents");
var pri = document.getElementById("ifmcontentstoprint").contentWindow;;

This expects this html to exist

<iframe id="ifmcontentstoprint" style="height: 0px; width: 0px; position: absolute"></iframe>

The other solution is to use the media selector and on the media="print" styles hide everything you don't want to print.

<style type="text/css" media="print">
   .no-print { display: none; }

Last way requires some work on the server. You can send all the HTML+CSS to the server and use one of many components to generate a printable document like PDF. I've tried setups doing this with PhantomJs.

How to convert List<string> to List<int>?

Using Linq ...

List<string> listofIDs = collection.AllKeys.ToList();  
List<int> myStringList = listofIDs.Select(s => int.Parse(s)).ToList();

Non greedy (reluctant) regex matching in sed?

sed does not support "non greedy" operator.

You have to use "[]" operator to exclude "/" from match.

sed 's,\(http://[^/]*\)/.*,\1,'

P.S. there is no need to backslash "/".

How do I delete from multiple tables using INNER JOIN in SQL server

You can take advantage of the "deleted" pseudo table in this example. Something like:

begin transaction;

   declare @deletedIds table ( id int );

   delete from t1
   output into @deletedIds
   from table1 as t1
    inner join table2 as t2
      on =
    inner join table3 as t3
      on =;

   delete from t2
   from table2 as t2
    inner join @deletedIds as d
      on =;

   delete from t3
   from table3 as t3 ...

commit transaction;

Obviously you can do an 'output deleted.' on the second delete as well, if you needed something to join on for the third table.

As a side note, you can also do inserted.* on an insert statement, and both inserted.* and deleted.* on an update statement.

EDIT: Also, have you considered adding a trigger on table1 to delete from table2 + 3? You'll be inside of an implicit transaction, and will also have the "inserted." and "deleted." pseudo-tables available.

In what situations would AJAX long/short polling be preferred over HTML5 WebSockets?

One contending technology you've omitted is Server-Sent Events / Event Source. What are Long-Polling, Websockets, Server-Sent Events (SSE) and Comet? has a good discussion of all of these. Keep in mind that some of these are easier than others to integrate with on the server side.

Firebase Permission Denied

OK, but you don`t want to open the whole realtime database! You need something like this.

  /* Visit to learn more about security rules. */
  "rules": {
    ".read": "auth.uid !=null",
    ".write": "auth.uid !=null"


  "rules": {
    "users": {
      "$uid": {
        ".write": "$uid === auth.uid"

Send HTTP GET request with header

You do it exactly as you showed with this line:

get.setHeader("Content-Type", "application/x-zip");

So your header is fine and the problem is some other input to the web service. You'll want to debug that on the server side.

how to use a like with a join in sql?

Using conditional criteria in a join is definitely different than the Where clause. The cardinality between the tables can create differences between Joins and Where clauses.

For example, using a Like condition in an Outer Join will keep all records in the first table listed in the join. Using the same condition in the Where clause will implicitly change the join to an Inner join. The record has to generally be present in both tables to accomplish the conditional comparison in the Where clause.

I generally use the style given in one of the prior answers.

tbl_A as ta
            ON ta.[Desc] LIKE '%' + tb.[Desc] + '%'

This way I can control the join type.

Sort JavaScript object by key

The one line:

  .sort(([keyA], [keyB]) => keyA > keyB)
  .reduce((obj, [key,value]) => Object.assign(obj, {[key]: value}), {})

How to check size of a file using Bash?

python -c 'import os; print (os.path.getsize("... filename ..."))'

portable, all flavours of python, avoids variation in stat dialects

Check if a variable is a string in JavaScript

function isString (obj) {
  return ( === '[object String]');

I saw that here:

How to create a DB link between two oracle instances

as a simple example:

  CONNECT TO _username_
    IDENTIFIED BY _passwd_

for more info:

Nuget connection attempt failed "Unable to load the service index for source"

nuget restore 


msbuild /t:restore

both didn't work for me with same error. But

dotnet restore 

worked perfect. Try that

Android studio- "SDK tools directory is missing"

when first installing android studio and everything, install sdk to a new file like C:\Android\sdk and make sure all the next setup sdk items point to the folder you installed sdk to. It will work fine now... it must have something to do with permissions in the appdata folder is what my guess is

What is the worst real-world macros/pre-processor abuse you've ever come across?

I would like to submit for the contest a gem called chaos-pp, which implements a functional language by means of the preprocessor macros.

One of the examples is calculating the 500th fibonacci number entirely by the preprocessor:

The original code before preprocessor looks as this:

int main(void) {
     ("The 500th Fibonacci number is "
   return 0;

preprocessing the file we get the following result (after a rather long wait):

$ cpp -I../inc fibonacci.c 2>/dev/null | tail
  return fib_iter(n, 0, 1);
# 63 "fibonacci.c"
int main(void) {
     ("The 500th Fibonacci number is "
   return 0;

What is "Linting"?

Lint was the name of a program that would go through your C code and identify problems before you compiled, linked, and ran it. It was a static checker, much like FindBugs today for Java.

Like Google, "lint" became a verb that meant static checking your source code.

Typescript empty object for a typed variable

user: USER

this.user = ({} as USER)

How to center a window on the screen in Tkinter?

This works also in Python 3.x and centers the window on screen:

from tkinter import *

app = Tk()
app.eval('tk::PlaceWindow . center')

How to fix "Headers already sent" error in PHP

Instead of the below line



echo("<script>location.href = '".ADMIN_URL."/index.php?msg=$msg';</script>");


?><script><?php echo("location.href = '".ADMIN_URL."/index.php?msg=$msg';");?></script><?php

It'll definitely solve your problem. I faced the same problem but I solved through writing header location in the above way.

Can I Set "android:layout_below" at Runtime Programmatically?

Kotlin version with infix function

infix fun View.below(view: View) {
      (this.layoutParams as? RelativeLayout.LayoutParams)?.addRule(RelativeLayout.BELOW,

Then you can write:

view1 below view2

Or you can call it as a normal function:


Ruby: How to iterate over a range, but in set increments?

rng.step(n=1) {| obj | block } => rng

Iterates over rng, passing each nth element to the block. If the range contains numbers or strings, natural ordering is used. Otherwise step invokes succ to iterate through range elements. The following code uses class Xs, which is defined in the class-level documentation.

range =
range.step(2) {|x| puts x}
range.step(3) {|x| puts x}


1 x
3 xxx
5 xxxxx
7 xxxxxxx
9 xxxxxxxxx
1 x
4 xxxx
7 xxxxxxx
10 xxxxxxxxxx



Xcode 12, building for iOS Simulator, but linking in object file built for iOS, for architecture arm64

In my case: Xcode 12

I set empty values on EXCLUDED_ARCHS and set ONLY_ACTIVE_ARCH Debug = YES Release = NO Project's Build Setting

and I included this in my Podfile:

post_install do |installer|
    installer.pods_project.targets.each do |target|
        target.build_configurations.each do |config|
            config.build_settings["EXCLUDED_ARCHS[sdk=iphonesimulator*]"] = "arm64"

It runs on my Simulator iPhone 8 (iOS 12) and iPhone 11 Pro Max (iOS 14) and on my device iPhone 7 Plus (iOS 13.4)

Set cursor position on contentEditable <div>

This is compatible with the standards-based browsers, but will probably fail in IE. I'm providing it as a starting point. IE doesn't support DOM Range.

var editable = document.getElementById('editable'),
    selection, range;

// Populates selection and range variables
var captureSelection = function(e) {
    // Don't capture selection outside editable region
    var isOrContainsAnchor = false,
        isOrContainsFocus = false,
        sel = window.getSelection(),
        parentAnchor = sel.anchorNode,
        parentFocus = sel.focusNode;

    while(parentAnchor && parentAnchor != document.documentElement) {
        if(parentAnchor == editable) {
            isOrContainsAnchor = true;
        parentAnchor = parentAnchor.parentNode;

    while(parentFocus && parentFocus != document.documentElement) {
        if(parentFocus == editable) {
            isOrContainsFocus = true;
        parentFocus = parentFocus.parentNode;

    if(!isOrContainsAnchor || !isOrContainsFocus) {

    selection = window.getSelection();

    // Get range (standards)
    if(selection.getRangeAt !== undefined) {
        range = selection.getRangeAt(0);

    // Get range (Safari 2)
    } else if(
        document.createRange &&
        selection.anchorNode &&
        selection.anchorOffset &&
        selection.focusNode &&
    ) {
        range = document.createRange();
        range.setStart(selection.anchorNode, selection.anchorOffset);
        range.setEnd(selection.focusNode, selection.focusOffset);
    } else {
        // Failure here, not handled by the rest of the script.
        // Probably IE or some older browser

// Recalculate selection while typing
editable.onkeyup = captureSelection;

// Recalculate selection after clicking/drag-selecting
editable.onmousedown = function(e) {
    editable.className = editable.className + ' selecting';
document.onmouseup = function(e) {
    if(editable.className.match(/\sselecting(\s|$)/)) {
        editable.className = editable.className.replace(/ selecting(\s|$)/, '');

editable.onblur = function(e) {
    var cursorStart = document.createElement('span'),
        collapsed = !!range.collapsed; = 'cursorStart';

    // Insert beginning cursor marker

    // Insert end cursor marker if any text is selected
    if(!collapsed) {
        var cursorEnd = document.createElement('span'); = 'cursorEnd';

// Add callbacks to afterFocus to be called after cursor is replaced
// if you like, this would be useful for styling buttons and so on
var afterFocus = [];
editable.onfocus = function(e) {
    // Slight delay will avoid the initial selection
    // (at start or of contents depending on browser) being mistaken
    setTimeout(function() {
        var cursorStart = document.getElementById('cursorStart'),
            cursorEnd = document.getElementById('cursorEnd');

        // Don't do anything if user is creating a new selection
        if(editable.className.match(/\sselecting(\s|$)/)) {
            if(cursorStart) {
            if(cursorEnd) {
        } else if(cursorStart) {
            var range = document.createRange();

            if(cursorEnd) {

                // Delete cursor markers

                // Select range
            } else {

                // Select range

                // Delete cursor marker
                document.execCommand('delete', false, null);

        // Call callbacks here
        for(var i = 0; i < afterFocus.length; i++) {
        afterFocus = [];

        // Register selection again
    }, 10);

Endless loop in C/C++

Everyone seems to like while (true):

According to SLaks, they compile identically.

Ben Zotto also says it doesn't matter:

It's not faster. If you really care, compile with assembler output for your platform and look to see. It doesn't matter. This never matters. Write your infinite loops however you like.

In response to user1216838, here's my attempt to reproduce his results.

Here's my machine:

cat /etc/*-release
CentOS release 6.4 (Final)

gcc version:

Target: x86_64-unknown-linux-gnu
Thread model: posix
gcc version 4.8.2 (GCC)

And test files:

// testing.cpp
#include <iostream>

int main() {
    do { break; } while(1);

// testing2.cpp
#include <iostream>

int main() {
    while(1) { break; }

// testing3.cpp
#include <iostream>

int main() {
    while(true) { break; }

The commands:

gcc -S -o test1.asm testing.cpp
gcc -S -o test2.asm testing2.cpp
gcc -S -o test3.asm testing3.cpp

cmp test1.asm test2.asm

The only difference is the first line, aka the filename.

test1.asm test2.asm differ: byte 16, line 1


        .file   "testing2.cpp"
        .local  _ZStL8__ioinit
        .comm   _ZStL8__ioinit,1,1
        .globl  main
        .type   main, @function
        pushq   %rbp
        .cfi_def_cfa_offset 16
        .cfi_offset 6, -16
        movq    %rsp, %rbp
        .cfi_def_cfa_register 6
        movl    $0, %eax
        popq    %rbp
        .cfi_def_cfa 7, 8
        .size   main, .-main
        .type   _Z41__static_initialization_and_destruction_0ii, @function
        pushq   %rbp
        .cfi_def_cfa_offset 16
        .cfi_offset 6, -16
        movq    %rsp, %rbp
        .cfi_def_cfa_register 6
        subq    $16, %rsp
        movl    %edi, -4(%rbp)
        movl    %esi, -8(%rbp)
        cmpl    $1, -4(%rbp)
        jne     .L3
        cmpl    $65535, -8(%rbp)
        jne     .L3
        movl    $_ZStL8__ioinit, %edi
        call    _ZNSt8ios_base4InitC1Ev
        movl    $__dso_handle, %edx
        movl    $_ZStL8__ioinit, %esi
        movl    $_ZNSt8ios_base4InitD1Ev, %edi
        call    __cxa_atexit
        .cfi_def_cfa 7, 8
        .size   _Z41__static_initialization_and_destruction_0ii, .-_Z41__static_initialization_and_destruction_0ii
        .type   _GLOBAL__sub_I_main, @function
        pushq   %rbp
        .cfi_def_cfa_offset 16
        .cfi_offset 6, -16
        movq    %rsp, %rbp
        .cfi_def_cfa_register 6
        movl    $65535, %esi
        movl    $1, %edi
        call    _Z41__static_initialization_and_destruction_0ii
        popq    %rbp
        .cfi_def_cfa 7, 8
        .size   _GLOBAL__sub_I_main, .-_GLOBAL__sub_I_main
        .section        .ctors,"aw",@progbits
        .align 8
        .quad   _GLOBAL__sub_I_main
        .hidden __dso_handle
        .ident  "GCC: (GNU) 4.8.2"
        .section        .note.GNU-stack,"",@progbits

With -O3, the output is considerably smaller of course, but still no difference.

Angular2 - TypeScript : Increment a number after timeout in AppComponent

This is not valid TypeScript code. You can not have method invocations in the body of a class.

export class AppComponent {
  public n: number = 1;
  setTimeout(function() {
    n = n + 10;
  }, 1000);

Instead move the setTimeout call to the constructor of the class. Additionally, use the arrow function => to gain access to this.

export class AppComponent {
  public n: number = 1;

  constructor() {
    setTimeout(() => {
      this.n = this.n + 10;
    }, 1000);


In TypeScript, you can only refer to class properties or methods via this. That's why the arrow function => is important.

See line breaks and carriage returns in editor

by using cat and -A you can see new lines as $, tabs as ^I
cat -A myfile

Install php-zip on php 5.6 on Ubuntu

Try either

  • sudo apt-get install php-zip or
  • sudo apt-get install php5.6-zip

Then, you might have to restart your web server.

  • sudo service apache2 restart or
  • sudo service nginx restart

If you are installing on centos or fedora OS then use yum in place of apt-get. example:-

sudo yum install php-zip or sudo yum install php5.6-zip and sudo service httpd restart

'pip install' fails for every package ("Could not find a version that satisfies the requirement")

Support for TLS 1.0 and 1.1 was dropped for PyPI. If your system does not use a more recent version, it could explain your error.

Could you try reinstalling pip system-wide, to update your system dependencies to a newer version of TLS?

This seems to be related to Unable to install Python libraries

See Dominique Barton's answer:

Apparently pip is trying to access PyPI via HTTPS (which is encrypted and fine), but with an old (insecure) SSL version. Your system seems to be out of date. It might help if you update your packages.

On Debian-based systems I'd try:

apt-get update && apt-get upgrade python-pip

On Red Hat Linux-based systems:

yum update python-pip # (or python2-pip, at least on Red Hat Linux 7)

On Mac:

sudo easy_install -U pip

You can also try to update openssl separately.

How to convert NSData to byte array in iPhone?

That's because the return type for [data bytes] is a void* c-style array, not a Uint8 (which is what Byte is a typedef for).

The error is because you are trying to set an allocated array when the return is a pointer type, what you are looking for is the getBytes:length: call which would look like:

[data getBytes:&byteData length:len];

Which fills the array you have allocated with data from the NSData object.

Value does not fall within the expected range

I had from a totaly different reason the same notice "Value does not fall within the expected range" from the Visual studio 2008 while trying to use the: Tools -> Windows Embedded Silverlight Tools -> Update Silverlight For Windows Embedded Project.

After spending many ohurs I found out that the problem was that there wasn't a resource file and the update tool looks for the .RC file

Therefor the solution is to add to the resource folder a .RC file and than it works perfectly. I hope it will help someone out there

How to use not contains() in xpath?

XPath queries are case sensitive. Having looked at your example (which, by the way, is awesome, nobody seems to provide examples anymore!), I can get the result you want just by changing "business", to "Business"


I have tested this by opening the XML file in Chrome, and using the Developer tools to execute that XPath queries, and it gave me just the Film category back.

Understanding string reversal via slicing

It's basic step notation, consider the functionality of:


What happens is the index is sliced between position 2 and 4, what the third variable does is it sets the step size starting from the first value. In this case it would return a[2], since a[4] is an upper bounds only two values are return and no second step takes place. The (-) minus operator simply reverses the step output.

How do you format a Date/Time in TypeScript?

I had a similar problem and I solved with this


Laravel password validation rule

A Custom Laravel Validation Rule will allow developers to provide a custom message with each use case for a better UX experience.

php artisan make:rule IsValidPassword

namespace App\Rules;

use Illuminate\Support\Str;
use Illuminate\Contracts\Validation\Rule;

class isValidPassword implements Rule
     * Determine if the Length Validation Rule passes.
     * @var boolean
    public $lengthPasses = true;

     * Determine if the Uppercase Validation Rule passes.
     * @var boolean
    public $uppercasePasses = true;

     * Determine if the Numeric Validation Rule passes.
     * @var boolean
    public $numericPasses = true;

     * Determine if the Special Character Validation Rule passes.
     * @var boolean
    public $specialCharacterPasses = true;

     * Determine if the validation rule passes.
     * @param  string  $attribute
     * @param  mixed  $value
     * @return bool
    public function passes($attribute, $value)
        $this->lengthPasses = (Str::length($value) >= 10);
        $this->uppercasePasses = (Str::lower($value) !== $value);
        $this->numericPasses = ((bool) preg_match('/[0-9]/', $value));
        $this->specialCharacterPasses = ((bool) preg_match('/[^A-Za-z0-9]/', $value));

        return ($this->lengthPasses && $this->uppercasePasses && $this->numericPasses && $this->specialCharacterPasses);

     * Get the validation error message.
     * @return string
    public function message()
        switch (true) {
            case ! $this->uppercasePasses
                && $this->numericPasses
                && $this->specialCharacterPasses:
                return 'The :attribute must be at least 10 characters and contain at least one uppercase character.';

            case ! $this->numericPasses
                && $this->uppercasePasses
                && $this->specialCharacterPasses:
                return 'The :attribute must be at least 10 characters and contain at least one number.';

            case ! $this->specialCharacterPasses
                && $this->uppercasePasses
                && $this->numericPasses:
                return 'The :attribute must be at least 10 characters and contain at least one special character.';

            case ! $this->uppercasePasses
                && ! $this->numericPasses
                && $this->specialCharacterPasses:
                return 'The :attribute must be at least 10 characters and contain at least one uppercase character and one number.';

            case ! $this->uppercasePasses
                && ! $this->specialCharacterPasses
                && $this->numericPasses:
                return 'The :attribute must be at least 10 characters and contain at least one uppercase character and one special character.';

            case ! $this->uppercasePasses
                && ! $this->numericPasses
                && ! $this->specialCharacterPasses:
                return 'The :attribute must be at least 10 characters and contain at least one uppercase character, one number, and one special character.';

                return 'The :attribute must be at least 10 characters.';

Then on your request validation:

    'email'    => 'required|string|email:filter',
    'password' => [
        new isValidPassword(),

'ssh-keygen' is not recognized as an internal or external command

I found an easy solution to fix this :

In the command prompt, go to your git\bin directory, and then execute your commands from here

XAMPP - Port 80 in use by "Unable to open process" with PID 4! 12

Click services on the Xampp control panel (filename is services.msc, extra info).

First, look for IIS, if it is running. Stop it (stop this service option on the left after clicking on the service name.). Then, this is the main problem, Look for Web deployment Service (not the exact name though it has Web deployment at the beginning.). Stop this service too. Try again and Apache should work.

If you are running Skype, exit out of that too, run Apache, then launch Skype

Expected corresponding JSX closing tag for input Reactjs

You need to close the input element with /> at the end. In React, we have to close every element. Your code should be:

<input id="icon_prefix" type="text" class="validate/">

Examples of good gotos in C or C++

I have nothing against gotos in general, but I can think of several reasons why you wouldn't want to use them for a loop like you mentioned:

  • It does not limit scope hence any temp variables you use inside won't be freed until later.
  • It does not limit scope hence it could lead to bugs.
  • It does not limit scope hence you cannot re-use the same variable names later in future code in the same scope.
  • It does not limit scope hence you have the chance of skipping over a variable declaration.
  • People are not accustomed to it and it will make your code harder to read.
  • Nested loops of this type can lead to spaghetti code, normals loops will not lead to spaghetti code.

Insert a background image in CSS (Twitter Bootstrap)

The problem can also be the ordering of your style sheet imports. I had to move my custom style sheet import below the bootstrap import.

How can I concatenate a string within a loop in JSTL/JSP?

Is JSTL's join(), what you searched for?

<c:set var="myVar" value="${fn:join(myParams.items, ' ')}" />

C: What is the difference between ++i and i++?

The Main Difference is

  • i++ Post(After Increment) and
  • ++i Pre (Before Increment)

    • post if i =1 the loop increments like 1,2,3,4,n
    • pre if i =1 the loop increments like 2,3,4,5,n

SQL server query to get the list of columns in a table along with Data types, NOT NULL, and PRIMARY KEY constraints

You could use the query:

where TABLE_NAME='TableName'

to get all the metadata you require except for the Pk information.

Provide static IP to docker containers via docker-compose

I was facing some difficulties with an environment variable that is with custom name (not with container name /port convention for KAPACITOR_BASE_URL and KAPACITOR_ALERTS_ENDPOINT). If we give service name in this case it wouldn't resolve the ip as

KAPACITOR_BASE_URL:  http://kapacitor:9092

In above http://[**kapacitor**]:9092 would not resolve to

I resolved the static IPs issues using subnetting configurations.

version: "3.3"

        - subnet:
        image: postgres:9.4.4
            - "5432:5432"
            - postgres_data:/var/lib/postgresql/data

        image: redis:latest
            - "6379"

        image: influxdb:latest
            - "8086:8086"
            - "8083:8083"
            - ../influxdb/influxdb.conf:/etc/influxdb/influxdb.conf
            - ../influxdb/inxdb:/var/lib/influxdb
          INFLUXDB_ADMIN_ENABLED: "true"
          INFLUXDB_USERNAME: "db_username"
          INFLUXDB_PASSWORD: "12345678"
          INFLUXDB_DB: db_customers

        image: kapacitor:latest
            - "9092:9092"
            - influxdb
            - ../kapacitor/kapacitor.conf:/etc/kapacitor/kapacitor.conf
            - ../kapacitor/kapdb:/var/lib/kapacitor
          KAPACITOR_INFLUXDB_0_URLS_0: http://influxdb:8086

        build: .
        command: bundle exec rails s -b
            - "3000:3000"
            - db
            - kapacitor
            - db
            - .:/var/app/current
          DATABASE_URL: postgres://postgres@db
          DATABASE_USERNAME: postgres
          DATABASE_PASSWORD: postgres
          INFLUX_URL: http://influxdb:8086
          INFLUX_USER: db_username
          INFLUX_PWD: 12345678


"Could not find bundler" error

According to this answer to a similar question, it should be enough:

rvmsudo gem install bundler.


duplicate 'row.names' are not allowed error

Another possible reason for this error is that you have entire rows duplicated. If that is the case, the problem is solved by removing the duplicate rows.

jQuery posting valid json in request body

An actual JSON request would look like this:

data: '{"command":"on"}',

Where you're sending an actual JSON string. For a more general solution, use JSON.stringify() to serialize an object to JSON, like this:

data: JSON.stringify({ "command": "on" }),

To support older browsers that don't have the JSON object, use json2.js which will add it in.

What's currently happening is since you have processData: false, it's basically sending this: ({"command":"on"}).toString() which is [object Object]...what you see in your request.

Apache won't follow symlinks (403 Forbidden)

Check that Apache has execute rights for /root, /root/site and /root/site/about.


chmod o+x /root /root/site /root/site/about

How to print binary tree diagram?

Here is another way to visualize your tree: save the nodes as an xml file and then let your browser show you the hierarchy:

class treeNode{
    int key;
    treeNode left;
    treeNode right;

    public treeNode(int key){
        this.key = key;
        left = right = null;

    public void printNode(StringBuilder output, String dir){
        output.append("<node key='" + key + "' dir='" + dir + "'>");
        if(left != null)
            left.printNode(output, "l");
        if(right != null)
            right.printNode(output, "r");

class tree{
    private treeNode treeRoot;

    public tree(int key){
        treeRoot = new treeNode(key);

    public void insert(int key){
        insert(treeRoot, key);

    private treeNode insert(treeNode root, int key){
        if(root == null){
            treeNode child = new treeNode(key);
            return child;

        if(key < root.key)
            root.left = insert(root.left, key);
        else if(key > root.key)
            root.right = insert(root.right, key);

        return root;

    public void saveTreeAsXml(){
        StringBuilder strOutput = new StringBuilder();
        strOutput.append("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
        treeRoot.printNode(strOutput, "root");
        try {
            PrintWriter writer = new PrintWriter("C:/tree.xml", "UTF-8");
        catch (FileNotFoundException e){

        catch(UnsupportedEncodingException e){


Here is code to test it:

    tree t = new tree(1);


And the output looks like this:

enter image description here

How can I parse String to Int in an Angular expression?

I tried the solutions mentioned above and none of them worked for me. I used JSON.parse and it worked:

  .success(function (data) {
    console.log('success: ' + data.length);

    if (JSON.stringify(data) != "not found") {
        $scope.adPoll = JSON.parse(data);
  .error(function (data) {
    console.log('Error: ' + data);

Writing JSON object to a JSON file with fs.writeFileSync

When sending data to a web server, the data has to be a string (here). You can convert a JavaScript object into a string with JSON.stringify(). Here is a working example:

var fs = require('fs');

var originalNote = {
  title: 'Meeting',
  description: 'Meeting John Doe at 10:30 am'

var originalNoteString = JSON.stringify(originalNote);

fs.writeFileSync('notes.json', originalNoteString);

var noteString = fs.readFileSync('notes.json');

var note = JSON.parse(noteString);

console.log(`TITLE: ${note.title} DESCRIPTION: ${note.description}`);

Hope it could help.

Find out how much memory is being used by an object in Python

There's no easy way to find out the memory size of a python object. One of the problems you may find is that Python objects - like lists and dicts - may have references to other python objects (in this case, what would your size be? The size containing the size of each object or not?). There are some pointers overhead and internal structures related to object types and garbage collection. Finally, some python objects have non-obvious behaviors. For instance, lists reserve space for more objects than they have, most of the time; dicts are even more complicated since they can operate in different ways (they have a different implementation for small number of keys and sometimes they over allocate entries).

There is a big chunk of code (and an updated big chunk of code) out there to try to best approximate the size of a python object in memory.

You may also want to check some old description about PyObject (the internal C struct that represents virtually all python objects).

How do I check if a type is a subtype OR the type of an object?


How do I read input character-by-character in Java?

If I were you I'd just use a scanner and use ".nextByte()". You can cast that to a char and you're good.

Try/catch does not seem to have an effect

It is also possible to set the error action preference on individual cmdlets, not just for the whole script. This is done using the parameter ErrorAction (alisa EA) which is available on all cmdlets.


 Write-Host $ErrorActionPreference; #Check setting for ErrorAction - the default is normally Continue
 get-item filethatdoesntexist; # Normally generates non-terminating exception so not caught
 write-host "You will hit me as exception from line above is non-terminating";  
 get-item filethatdoesntexist -ErrorAction Stop; #Now ErrorAction parameter with value Stop causes exception to be caught 
 write-host "you won't reach me as exception is now caught";
 Write-Host "Caught the exception";
 Write-Host $Error[0].Exception;

How to join two tables by multiple columns in SQL?

You would basically want something along the lines of:

SELECT e.*, v.Score
  FROM Evaluation e
ON v.CaseNum = e.CaseNum AND
v.FileNum = e.FileNum AND
v.ActivityNum = e.ActivityNum;

Why SpringMVC Request method 'GET' not supported?

Apparently some POST requests looks like a "GET" to the server (like Heroku...)

So I use this strategy and it works for me:

@RequestMapping(value = "/salvar", method = { RequestMethod.GET, RequestMethod.POST })

How to show Snackbar when Activity starts?

call this method in onCreate

Snackbar snack = Snackbar.make(
                    (((Activity) context).findViewById(,
                    message + "", Snackbar.LENGTH_SHORT);
snack.setDuration(Snackbar.LENGTH_INDEFINITE);//change Duration as you need
            //snack.setAction(actionButton, new View.OnClickListener());//add your own listener
            View view = snack.getView();
            TextView tv = (TextView) view
            tv.setTextColor(Color.WHITE);//change textColor

            TextView tvAction = (TextView) view


Get all object attributes in Python?

I use __dict__


class MyObj(object):
  def __init__(self): = 'Chuck Norris' = '+6661'

obj = MyObj()

# Output:  
# {'phone': '+6661', 'name': 'Chuck Norris'}